Dr. Arun Majumdar

All Publications

• Spin disorder control of topological spin texture. Nature communications Zhang, H., Shao, Y. T., Chen, X., Zhang, B., Wang, T., Meng, F., Xu, K., Meisenheimer, P., Chen, X., Huang, X., Behera, P., Husain, S., Zhu, T., Pan, H., Jia, Y., Settineri, N., Giles-Donovan, N., He, Z., Scholl, A., N'Diaye, A., Shafer, P., Raja, A., Xu, C., Martin, L. W., Crommie, M. F., Yao, J., Qiu, Z., Majumdar, A., Bellaiche, L., Muller, D. A., Birgeneau, R. J., Ramesh, R. 2024; 15 (1): 3828

  Abstract

  Stabilization of topological spin textures in layered magnets has the potential to drive the development of advanced low-dimensional spintronics devices. However, achieving reliable and flexible manipulation of the topological spin textures beyond skyrmion in a two-dimensional magnet system remains challenging. Here, we demonstrate the introduction of magnetic iron atoms between the van der Waals gap of a layered magnet, Fe3GaTe2, to modify local anisotropic magnetic interactions. Consequently, we present direct observations of the order-disorder skyrmion lattices transition. In addition, non-trivial topological solitons, such as skyrmioniums and skyrmion bags, are realized at room temperature. Our work highlights the influence of random spin control of non-trivial topological spin textures.

  View details for DOI 10.1038/s41467-024-47715-5

  View details for PubMedID 38714653

  View details for PubMedCentralID PMC11076609

• Exploring the potential of non-residential solar to tackle energy injustice NATURE ENERGY Wussow, M., Zanocco, C., Wang, Z., Prabha, R., Flora, J., Neumann, D., Majumdar, A., Rajagopal, R. 2024

  View details for DOI 10.1038/s41560-024-01485-y

  View details for Web of Science ID 001194849700001

• Geospatial mapping of distribution grid with machine learning and publicly-accessible multi-modal data. Nature communications Wang, Z., Majumdar, A., Rajagopal, R. 2023; 14 (1): 5006

  Abstract

  Detailed and location-aware distribution grid information is a prerequisite for various power system applications such as renewable energy integration, wildfire risk assessment, and infrastructure planning. However, a generalizable and scalable approach to obtain such information is still lacking. In this work, we develop a machine-learning-based framework to map both overhead and underground distribution grids using widely-available multi-modal data including street view images, road networks, and building maps. Benchmarked against the utility-owned distribution grid map in California, our framework achieves>80% precision and recall on average in the geospatial mapping of grids. The framework developed with the California data can be transferred to Sub-Saharan Africa and maintain the same level of precision without fine-tuning, demonstrating its generalizability. Furthermore, our framework achieves a R2 of 0.63 in measuring the fraction of underground power lines at the aggregate level for estimating grid exposure to wildfires. We offer the framework as an open tool for mapping and analyzing distribution grids solely based on publicly-accessible data to support the construction and maintenance of reliable and clean energy systems around the world.

  View details for DOI 10.1038/s41467-023-39647-3

  View details for PubMedID 37591846

• Local and utility-wide cost allocations for a more equitable wildfire-resilient distribution grid NATURE ENERGY Wang, Z., Wara, M., Majumdar, A., Rajagopal, R. 2023

  View details for DOI 10.1038/s41560-023-01306-8

  View details for Web of Science ID 001044206100003

• Imaging the electron charge density in monolayer MoS2 at the Ångstrom scale. Nature communications Martis, J., Susarla, S., Rayabharam, A., Su, C., Paule, T., Pelz, P., Huff, C., Xu, X., Li, H. K., Jaikissoon, M., Chen, V., Pop, E., Saraswat, K., Zettl, A., Aluru, N. R., Ramesh, R., Ercius, P., Majumdar, A. 2023; 14 (1): 4363

  Abstract

  Four-dimensional scanning transmission electron microscopy (4D-STEM) has recently gained widespread attention for its ability to image atomic electric fields with sub-Ångstrom spatial resolution. These electric field maps represent the integrated effect of the nucleus, core electrons and valence electrons, and separating their contributions is non-trivial. In this paper, we utilized simultaneously acquired 4D-STEM center of mass (CoM) images and annular dark field (ADF) images to determine the projected electron charge density in monolayer MoS2. We evaluate the contributions of both the core electrons and the valence electrons to the derived electron charge density; however, due to blurring by the probe shape, the valence electron contribution forms a nearly featureless background while most of the spatial modulation comes from the core electrons. Our findings highlight the importance of probe shape in interpreting charge densities derived from 4D-STEM and the need for smaller electron probes.

  View details for DOI 10.1038/s41467-023-39304-9

  View details for PubMedID 37474521

• Fluids and Electrolytes under Confinement in Single-Digit Nanopores. Chemical reviews Aluru, N. R., Aydin, F., Bazant, M. Z., Blankschtein, D., Brozena, A. H., de Souza, J. P., Elimelech, M., Faucher, S., Fourkas, J. T., Koman, V. B., Kuehne, M., Kulik, H. J., Li, H., Li, Y., Li, Z., Majumdar, A., Martis, J., Misra, R. P., Noy, A., Pham, T. A., Qu, H., Rayabharam, A., Reed, M. A., Ritt, C. L., Schwegler, E., Siwy, Z., Strano, M. S., Wang, Y., Yao, Y., Zhan, C., Zhang, Z. 2023

  Abstract

  Confined fluids and electrolyte solutions in nanopores exhibit rich and surprising physics and chemistry that impact the mass transport and energy efficiency in many important natural systems and industrial applications. Existing theories often fail to predict the exotic effects observed in the narrowest of such pores, called single-digit nanopores (SDNs), which have diameters or conduit widths of less than 10 nm, and have only recently become accessible for experimental measurements. What SDNs reveal has been surprising, including a rapidly increasing number of examples such as extraordinarily fast water transport, distorted fluid-phase boundaries, strong ion-correlation and quantum effects, and dielectric anomalies that are not observed in larger pores. Exploiting these effects presents myriad opportunities in both basic and applied research that stand to impact a host of new technologies at the water-energy nexus, from new membranes for precise separations and water purification to new gas permeable materials for water electrolyzers and energy-storage devices. SDNs also present unique opportunities to achieve ultrasensitive and selective chemical sensing at the single-ion and single-molecule limit. In this review article, we summarize the progress on nanofluidics of SDNs, with a focus on the confinement effects that arise in these extremely narrow nanopores. The recent development of precision model systems, transformative experimental tools, and multiscale theories that have played enabling roles in advancing this frontier are reviewed. We also identify new knowledge gaps in our understanding of nanofluidic transport and provide an outlook for the future challenges and opportunities at this rapidly advancing frontier.

  View details for DOI 10.1021/acs.chemrev.2c00155

  View details for PubMedID 36898130

• Transport Mediating Core-Shell Photocatalyst Architecture for Selective Alkane Oxidation. Nano letters Xie, C., Sun, E., Wan, G., Zheng, J., Gupta, R., Majumdar, A. 2023

  Abstract

  The high activation barrier of the C-H bond in methane, combined with the high propensity of methanol and other liquid oxygenates toward overoxidation to CO2, have historically posed significant scientific and industrial challenges to the selective and direct conversion of methane to energy-dense fuels and chemical feedstocks. Here, we report a unique core-shell nanostructured photocatalyst, silica encapsulated TiO2 decorated with AuPd nanoparticles (TiO2@SiO2-AuPd), that prevents methanol overoxidation on its surface and possesses high selectivity and yield of oxygenates even at high UV intensity. This room-temperature approach achieves high selectivity for oxygenates (94.5%) with a total oxygenate yield of 15.4 mmol/gcat·h at 9.65 bar total pressure of CH4 and O2. The working principles of this core-shell photocatalyst were also systematically investigated. This design concept was further demonstrated to be generalizable for the selective oxidation of other alkanes.

  View details for DOI 10.1021/acs.nanolett.2c04567

  View details for PubMedID 36689625

• Iron-Poor Ferrites for Low-Temperature CO2 Conversion via Reverse Water-Gas Shift Thermochemical Looping ACS SUSTAINABLE CHEMISTRY & ENGINEERING Rojas, J., Sun, E., Wan, G., Oh, J., Randall, R., Haribal, V., Jung, I., Gupta, R., Majumdar, A. 2022

  View details for DOI 10.1021/acssuschemeng.2c03196

  View details for Web of Science ID 000855627400001

• Thermodynamic guiding principles of high-capacity phase transformation materials for splitting H2O and CO2 by thermochemical looping JOURNAL OF MATERIALS CHEMISTRY A Zhai, S., Nam, J., Sai Gautam, G., Lim, K., Rojas, J., Toney, M. F., Carter, E. A., Jung, I., Chueh, W. C., Majumdar, A. 2022

  View details for DOI 10.1039/d1ta10391a

  View details for Web of Science ID 000745805100001

• The use of poly-cation oxides to lower the temperature of two-step thermochemical water splitting ENERGY & ENVIRONMENTAL SCIENCE Zhai, S., Rojas, J., Ahlborg, N., Lim, K., Toney, M. F., Jin, H., Chueh, W. C., Majumdar, A. 2018; 11 (8): 2172–78

  View details for DOI 10.1039/c8ee00050f

  View details for Web of Science ID 000442262900024

• A dual-mode textile for human body radiative heating and cooling SCIENCE ADVANCES Hsu, P., Liu, C., Song, A. Y., Zhang, Z., Peng, Y., Xie, J., Liu, K., Wu, C., Catrysse, P. B., Cai, L., Zhai, S., Majumdar, A., Fan, S., Cui, Y. 2017; 3 (11): e1700895

  Abstract

  Maintaining human body temperature is one of the most basic needs for living, which often consumes a huge amount of energy to keep the ambient temperature constant. To expand the ambient temperature range while maintaining human thermal comfort, the concept of personal thermal management has been recently demonstrated in heating and cooling textiles separately through human body infrared radiation control. Realizing these two opposite functions within the same textile would represent an exciting scientific challenge and a significant technological advancement. We demonstrate a dual-mode textile that can perform both passive radiative heating and cooling using the same piece of textile without any energy input. The dual-mode textile is composed of a bilayer emitter embedded inside an infrared-transparent nanoporous polyethylene (nanoPE) layer. We demonstrate that the asymmetrical characteristics of both emissivity and nanoPE thickness can result in two different heat transfer coefficients and achieve heating when the low-emissivity layer is facing outside and cooling by wearing the textile inside out when the high-emissivity layer is facing outside. This can expand the thermal comfort zone by 6.5°C. Numerical fitting of the data further predicts 14.7°C of comfort zone expansion for dual-mode textiles with large emissivity contrast.

  View details for PubMedID 29296678

• Heterodyne x-ray diffuse scattering from coherent phonons STRUCTURAL DYNAMICS Kozina, M., Trigo, M., Chollet, M., Clark, J. N., Glownia, J. M., Gossard, A. C., Henighan, T., Jiang, M. P., Lu, H., Majumdar, A., Zhu, D., Reis, D. A. 2017; 4 (5): 054305

  Abstract

  Here, we report Fourier-transform inelastic x-ray scattering measurements of photoexcited GaAs with embedded ErAs nanoparticles. We observe temporal oscillations in the x-ray scattering intensity, which we attribute to inelastic scattering from coherent acoustic phonons. Unlike in thermal equilibrium, where inelastic x-ray scattering is proportional to the phonon occupation, we show that the scattering is proportional to the phonon amplitude for coherent states. The wavevectors of the observed phonons extend beyond the excitation wavevector. The nanoparticles break the discrete translational symmetry of the lattice, enabling the generation of large wavevector coherent phonons. Elastic scattering of x-ray photons from the nanoparticles provides a reference for heterodyne mixing, yielding signals proportional to the phonon amplitude.

  View details for DOI 10.1063/1.4989401

  View details for Web of Science ID 000414175400009

  View details for PubMedID 28852687

  View details for PubMedCentralID PMC5552389

• Evaluation of a Silicon Sr-90 Betavoltaic Power Source SCIENTIFIC REPORTS Dixon, J., Rajan, A., Bohlemann, S., Coso, D., Upadhyaya, A. D., Rohatgi, A., Chu, S., Majumdar, A., Yee, S. 2016; 6

  Abstract

  Betavoltaic energy converters (i.e., β-batteries) are attractive power sources because of their potential for high energy densities (>200 MWh/kg) and long duration continuous discharge (>1 year). However, conversion efficiencies have been historically low (<3%). High efficiency devices can be achieved by matching β-radiation transport length scales with the device physics length scales. In this work, the efficiency of c-Si devices using high-energy (>1 MeV) electrons emitted from (90)Sr as a power source is investigated. We propose a design for a >10% efficient betavoltaic device, which generates 1 W of power. A Varian Clinac iX is used to simulate the high-energy electrons emitted from (90)Sr, and a high efficiency c-Si photovoltaic cell is used as the converter. The measured conversion efficiency is 16%. This relatively high value is attributed to proper length scale matching and the generation of secondary electrons in c-Si by the primary β-particles.

  View details for DOI 10.1038/srep38182

  View details for Web of Science ID 000388995400001

  View details for PubMedCentralID PMC5131278

• Sr Betavoltaic Power Source. Scientific reports Dixon, J., Rajan, A., Bohlemann, S., Coso, D., Upadhyaya, A. D., Rohatgi, A., Chu, S., Majumdar, A., Yee, S. 2016; 6: 38182-?

  Abstract

  Betavoltaic energy converters (i.e., β-batteries) are attractive power sources because of their potential for high energy densities (>200 MWh/kg) and long duration continuous discharge (>1 year). However, conversion efficiencies have been historically low (<3%). High efficiency devices can be achieved by matching β-radiation transport length scales with the device physics length scales. In this work, the efficiency of c-Si devices using high-energy (>1 MeV) electrons emitted from (90)Sr as a power source is investigated. We propose a design for a >10% efficient betavoltaic device, which generates 1 W of power. A Varian Clinac iX is used to simulate the high-energy electrons emitted from (90)Sr, and a high efficiency c-Si photovoltaic cell is used as the converter. The measured conversion efficiency is 16%. This relatively high value is attributed to proper length scale matching and the generation of secondary electrons in c-Si by the primary β-particles.

  View details for DOI 10.1038/srep38182

  View details for PubMedID 27905521

  View details for PubMedCentralID PMC5131278

• Elucidating the synergistic mechanism of nickel-molybdenum electrocatalysts for the hydrogen evolution reaction MRS COMMUNICATIONS Mckay, I. S., Schwalbe, J. A., Goodman, E. D., Willis, J. J., Majumdar, A., Cargnello, M. 2016; 6 (3): 241-246

  View details for DOI 10.1557/mrc.2016.27

  View details for Web of Science ID 000389137400013

• Label-Free Electrical Detection of Enzymatic Reactions in Nanochannels. ACS nano Duan, C., Alibakhshi, M. A., Kim, D., Brown, C. M., Craik, C. S., Majumdar, A. 2016; 10 (8): 7476-7484

  Abstract

  We report label-free electrical detection of enzymatic reactions using 2-D nanofluidic channels and investigate reaction kinetics of enzymatic reactions on immobilized substrates in nanoscale-confined spaces. Trypsin proteolysis is chosen for demonstration of the detection scheme. When trypsin cleaves poly-l-lysine coated on the surface of silica nanochannels, the resulting change of surface charge density can be detected by monitoring the ionic conductance of the nanochannels. Our results show that detection of such surface enzymatic reactions is faster than detection of surface binding reactions in nanochannels for low-concentration analytes. Furthermore, the nanochannel sensor has a sensitivity down to 5 ng/mL, which statistically corresponds to a single enzyme per nanochannel. Our results also suggest that enzyme kinetics in nanochannels is fundamentally different from that in bulk solutions or plain surfaces. Such enzymatic reactions form two clear self-propagating reaction fronts inside the nanochannels, and the reaction fronts follow square-root time dependences at high enzyme concentrations due to significant nonspecific adsorption. However, at low enzyme concentrations when nonspecific adsorption is negligible, the reaction fronts propagate linearly with time, and the corresponding propagation speed is related to the channel geometry, enzyme concentration, catalytic reaction constant, diffusion coefficient, and substrate surface density. Optimization of this nanochannel sensor could lead to a quick-response, highly sensitive, and label-free sensor for enzyme assay and kinetic studies.

  View details for DOI 10.1021/acsnano.6b02062

  View details for PubMedID 27472431

• Nanoscale thermal transport. II. 2003-2012 APPLIED PHYSICS REVIEWS Cahill, D. G., Braun, P. V., Chen, G., Clarke, D. R., Fan, S., Goodson, K. E., Keblinski, P., King, W. P., Mahan, G. D., Majumdar, A., Maris, H. J., Phillpot, S. R., Pop, E., Shi, L. 2014; 1 (1)

  View details for DOI 10.1063/1.4832615

  View details for Web of Science ID 000334098500010

• Crossover from incoherent to coherent phonon scattering in epitaxial oxide superlattices NATURE MATERIALS Ravichandran, J., Yadav, A. K., Cheaito, R., Rossen, P. B., Soukiassian, A., Suresha, S. J., Duda, J. C., Foley, B. M., Lee, C., Zhu, Y., Lichtenberger, A. W., Moore, J. E., Muller, D. A., Schlom, D. G., Hopkins, P. E., Majumdar, A., Ramesh, R., Zurbuchen, M. A. 2014; 13 (2): 168-172

  Abstract

  Elementary particles such as electrons or photons are frequent subjects of wave-nature-driven investigations, unlike collective excitations such as phonons. The demonstration of wave-particle crossover, in terms of macroscopic properties, is crucial to the understanding and application of the wave behaviour of matter. We present an unambiguous demonstration of the theoretically predicted crossover from diffuse (particle-like) to specular (wave-like) phonon scattering in epitaxial oxide superlattices, manifested by a minimum in lattice thermal conductivity as a function of interface density. We do so by synthesizing superlattices of electrically insulating perovskite oxides and systematically varying the interface density, with unit-cell precision, using two different epitaxial-growth techniques. These observations open up opportunities for studies on the wave nature of phonons, particularly phonon interference effects, using oxide superlattices as model systems, with extensive applications in thermoelectrics and thermal management.

  View details for DOI 10.1038/NMAT3826

  View details for Web of Science ID 000330182700023

  View details for PubMedID 24317186

• Opportunities and challenges for a sustainable energy future NATURE Chu, S., Majumdar, A. 2012; 488 (7411): 294-303

  Abstract

  Access to clean, affordable and reliable energy has been a cornerstone of the world's increasing prosperity and economic growth since the beginning of the industrial revolution. Our use of energy in the twenty-first century must also be sustainable. Solar and water-based energy generation, and engineering of microbes to produce biofuels are a few examples of the alternatives. This Perspective puts these opportunities into a larger context by relating them to a number of aspects in the transportation and electricity generation sectors. It also provides a snapshot of the current energy landscape and discusses several research and development opportunities and pathways that could lead to a prosperous, sustainable and secure energy future for the world.

  View details for DOI 10.1038/nature11475

  View details for Web of Science ID 000307501000028

  View details for PubMedID 22895334

• Nanostructured Thermoelectrics: Big Efficiency Gains from Small Features ADVANCED MATERIALS Vineis, C. J., Shakouri, A., Majumdar, A., Kanatzidis, M. G. 2010; 22 (36): 3970-3980

  Abstract

  The field of thermoelectrics has progressed enormously and is now growing steadily because of recently demonstrated advances and strong global demand for cost-effective, pollution-free forms of energy conversion. Rapid growth and exciting innovative breakthroughs in the field over the last 10-15 years have occurred in large part due to a new fundamental focus on nanostructured materials. As a result of the greatly increased research activity in this field, a substantial amount of new data--especially related to materials--have been generated. Although this has led to stronger insight and understanding of thermoelectric principles, it has also resulted in misconceptions and misunderstanding about some fundamental issues. This article sets out to summarize and clarify the current understanding in this field; explain the underpinnings of breakthroughs reported in the past decade; and provide a critical review of various concepts and experimental results related to nanostructured thermoelectrics. We believe recent achievements in the field augur great possibilities for thermoelectric power generation and cooling, and discuss future paths forward that build on these exciting nanostructuring concepts.

  View details for DOI 10.1002/adma.201000839

  View details for Web of Science ID 000283104600001

  View details for PubMedID 20661949

• Nanowires for Enhanced Boiling Heat Transfer NANO LETTERS Chen, R., Lu, M., Srinivasan, V., Wang, Z., Cho, H. H., Majumdar, A. 2009; 9 (2): 548-553

  Abstract

  Boiling is a common mechanism for liquid-vapor phase transition and is widely exploited in power generation and refrigeration devices and systems. The efficacy of boiling heat transfer is characterized by two parameters: (a) heat transfer coefficient (HTC) or the thermal conductance; (b) the critical heat flux (CHF) limit that demarcates the transition from high HTC to very low HTC. While increasing the CHF and the HTC has significant impact on system-level energy efficiency, safety, and cost, their values for water and other heat transfer fluids have essentially remained unchanged for many decades. Here we report that the high surface tension forces offered by liquids in nanowire arrays made of Si and Cu can be exploited to increase both the CHF and the HTC by more than 100%.

  View details for DOI 10.1021/nl8026857

  View details for Web of Science ID 000263298700008

  View details for PubMedID 19152275

• Enhanced thermoelectric performance of rough silicon nanowires NATURE Hochbaum, A. I., Chen, R., Delgado, R. D., Liang, W., Garnett, E. C., Najarian, M., Majumdar, A., Yang, P. 2008; 451 (7175): 163-U5

  Abstract

  Approximately 90 per cent of the world's power is generated by heat engines that use fossil fuel combustion as a heat source and typically operate at 30-40 per cent efficiency, such that roughly 15 terawatts of heat is lost to the environment. Thermoelectric modules could potentially convert part of this low-grade waste heat to electricity. Their efficiency depends on the thermoelectric figure of merit ZT of their material components, which is a function of the Seebeck coefficient, electrical resistivity, thermal conductivity and absolute temperature. Over the past five decades it has been challenging to increase ZT > 1, since the parameters of ZT are generally interdependent. While nanostructured thermoelectric materials can increase ZT > 1 (refs 2-4), the materials (Bi, Te, Pb, Sb, and Ag) and processes used are not often easy to scale to practically useful dimensions. Here we report the electrochemical synthesis of large-area, wafer-scale arrays of rough Si nanowires that are 20-300 nm in diameter. These nanowires have Seebeck coefficient and electrical resistivity values that are the same as doped bulk Si, but those with diameters of about 50 nm exhibit 100-fold reduction in thermal conductivity, yielding ZT = 0.6 at room temperature. For such nanowires, the lattice contribution to thermal conductivity approaches the amorphous limit for Si, which cannot be explained by current theories. Although bulk Si is a poor thermoelectric material, by greatly reducing thermal conductivity without much affecting the Seebeck coefficient and electrical resistivity, Si nanowire arrays show promise as high-performance, scalable thermoelectric materials.

  View details for DOI 10.1038/nature06381

  View details for Web of Science ID 000252214400036

  View details for PubMedID 18185582

• Thermoelectricity in molecular junctions SCIENCE Reddy, P., Jang, S., Segalman, R. A., Majumdar, A. 2007; 315 (5818): 1568-1571

  Abstract

  By trapping molecules between two gold electrodes with a temperature difference across them, the junction Seebeck coefficients of 1,4-benzenedithiol (BDT), 4,4'-dibenzenedithiol, and 4,4''-tribenzenedithiol in contact with gold were measured at room temperature to be +8.7 +/- 2.1 microvolts per kelvin (muV/K), +12.9 +/- 2.2 muV/K, and +14.2 +/- 3.2 muV/K, respectively (where the error is the full width half maximum of the statistical distributions). The positive sign unambiguously indicates p-type (hole) conduction in these heterojunctions, whereas the Au Fermi level position for Au-BDT-Au junctions was identified to be 1.2 eV above the highest occupied molecular orbital level of BDT. The ability to study thermoelectricity in molecular junctions provides the opportunity to address these fundamental unanswered questions about their electronic structure and to begin exploring molecular thermoelectric energy conversion.

  View details for DOI 10.1126/science.1137149

  View details for Web of Science ID 000244934800050

  View details for PubMedID 17303718

• Rectification of ionic current in a nanofluidic diode NANO LETTERS Karnik, R., Duan, C., Castelino, K., Daiguji, H., Majumdar, A. 2007; 7 (3): 547-551

  Abstract

  We demonstrate rectification of ionic transport in a nanofluidic diode fabricated by introducing a surface charge discontinuity in a nanofluidic channel. Device current-voltage (I-V) characteristics agree qualitatively with a one-dimensional model at moderate to high ionic concentrations. This study illustrates ionic flow control using surface charge patterning in nanofluidic channels under high bias voltages.

  View details for DOI 10.1021/nl062806o

  View details for Web of Science ID 000244867400002

  View details for PubMedID 17311461

• Solid-state thermal rectifier SCIENCE Chang, C. W., Okawa, D., Majumdar, A., Zettl, A. 2006; 314 (5802): 1121-1124

  Abstract

  We demonstrated nanoscale solid-state thermal rectification. High-thermal-conductivity carbon and boron nitride nanotubes were mass-loaded externally and inhomogeneously with heavy molecules. The resulting nanoscale system yields asymmetric axial thermal conductance with greater heat flow in the direction of decreasing mass density. The effect cannot be explained by ordinary perturbative wave theories, and instead we suggest that solitons may be responsible for the phenomenon. Considering the important role of electrical rectifiers (diodes) in electronics, thermal rectifiers have substantial implications for diverse thermal management problems, ranging from nanoscale calorimeters to microelectronic processors to macroscopic refrigerators and energy-saving buildings.

  View details for DOI 10.1126/science.1132898

  View details for Web of Science ID 000242045800037

  View details for PubMedID 17110571

• Thermal conductivity reduction and thermoelectric figure of merit increase by embedding nanoparticles in crystalline semiconductors PHYSICAL REVIEW LETTERS Kim, W., Zide, J., Gossard, A., Klenov, D., Stemmer, S., Shakouri, A., Majumdar, A. 2006; 96 (4)

  Abstract

  Atomic substitution in alloys can efficiently scatter phonons, thereby reducing the thermal conductivity in crystalline solids to the "alloy limit." Using In0.53Ga0.47As containing ErAs nanoparticles, we demonstrate thermal conductivity reduction by almost a factor of 2 below the alloy limit and a corresponding increase in the thermoelectric figure of merit by a factor of 2. A theoretical model suggests that while point defects in alloys efficiently scatter short-wavelength phonons, the ErAs nanoparticles provide an additional scattering mechanism for the mid-to-long-wavelength phonons.

  View details for DOI 10.1103/PhysRevLett.96.045901

  View details for Web of Science ID 000235083600058

  View details for PubMedID 16486849

• Thermal conductance and thermopower of an individual single-wall carbon nanotube NANO LETTERS Yu, C. H., Shi, L., Yao, Z., Li, D. Y., Majumdar, A. 2005; 5 (9): 1842-1846

  Abstract

  We have observed experimentally that the thermal conductance of a 2.76-microm-long individual suspended single-wall carbon nanotube (SWCNT) was very close to the calculated ballistic thermal conductance of a 1-nm-diameter SWCNT without showing signatures of phonon-phonon Umklapp scattering for temperatures between 110 and 300 K. Although the observed thermopower of the SWCNT can be attributed to a linear diffusion contribution and a constant phonon drag effect, there could be an additional contact effect.

  View details for DOI 10.1021/nl051044e

  View details for Web of Science ID 000231945500039

  View details for PubMedID 16159235

• DNA translocation in inorganic nanotubes NANO LETTERS Fan, R., Karnik, R., Yue, M., Li, D. Y., Majumdar, A., Yang, P. D. 2005; 5 (9): 1633-1637

  Abstract

  Inorganic nanotubes were successfully integrated with microfluidic systems to create nanofluidic devices for single DNA molecule sensing. Inorganic nanotubes are unique in their high aspect ratio and exhibit translocation characteristics in which the DNA is fully stretched. Transient changes of ionic current indicate DNA translocation events. A transition from current decrease to current enhancement during translocation was observed on changing the buffer concentration, suggesting interplay between electrostatic charge and geometric blockage effects. These inorganic nanotube nanofluidic devices represent a new platform for the study of single biomolecule translocation with the potential for integration into nanofluidic circuits.

  View details for DOI 10.1021/nl0509677

  View details for Web of Science ID 000231945500001

  View details for PubMedID 16159197

• Electrostatic control of ions and molecules in nanofluidic transistors NANO LETTERS Karnik, R., Fan, R., Yue, M., Li, D. Y., Yang, P. D., Majumdar, A. 2005; 5 (5): 943-948

  Abstract

  We report a nanofluidic transistor based on a metal-oxide-solution (MOSol) system that is similar to a metal-oxide-semiconductor field-effect transistor (MOSFET). Using a combination of fluorescence and electrical measurements, we demonstrate that gate voltage modulates the concentration of ions and molecules in the channel and controls the ionic conductance. Our results illustrate the efficacy of field-effect control in nanofluidics, which could have broad implications on integrated nanofluidic circuits for manipulation of ions and biomolecules in sub-femtoliter volumes.

  View details for DOI 10.1021/nl050493b

  View details for Web of Science ID 000229120900023

  View details for PubMedID 15884899

• A 2-D microcantilever array for multiplexed biomolecular analysis JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Yue, M., Lin, H., Dedrick, D. E., Satyanarayana, S., Majumdar, A., Bedekar, A. S., Jenkins, J. W., Sundaram, S. 2004; 13 (2): 290-299

  View details for DOI 10.1109/JMEMS.2003.823216

  View details for Web of Science ID 000220759300016

• Thermoelectricity in semiconductor nanostructures SCIENCE Majumdar, A. 2004; 303 (5659): 777-778

  View details for Web of Science ID 000188753800037

• Thermal conductivity of individual silicon nanowires APPLIED PHYSICS LETTERS Li, D. Y., Wu, Y. Y., Kim, P., Shi, L., Yang, P. D., Majumdar, A. 2003; 83 (14): 2934-2936

  View details for DOI 10.1063/1.1616981

  View details for Web of Science ID 000185664000068

• Nanoscale thermal transport JOURNAL OF APPLIED PHYSICS Cahill, D. G., FORD, W. K., Goodson, K. E., Mahan, G. D., Majumdar, A., Maris, H. J., Merlin, R., Phillpot, S. R. 2003; 93 (2): 793-818

  View details for DOI 10.1063/1.1524305

  View details for Web of Science ID 000180134200001

• Thermometry and thermal transport in micro/nanoscale solid-state devices and structures JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME Cahill, D. G., Goodson, K. E., Majumdar, A. 2002; 124 (2): 223-241

  View details for DOI 10.1115/1.1454111

  View details for Web of Science ID 000175917200002

• Thermal transport measurements of individual multiwalled nanotubes PHYSICAL REVIEW LETTERS Kim, P., Shi, L., Majumdar, A., McEuen, P. L. 2001; 87 (21)

  Abstract

  The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W/K m at room temperature, which is 2 orders of magnitude higher than the estimation from previous experiments that used macroscopic mat samples. The temperature dependence of the thermal conductivity of nanotubes exhibits a peak at 320 K due to the onset of umklapp phonon scattering. The measured thermoelectric power shows linear temperature dependence with a value of 80 microV/K at room temperature.

  View details for DOI 10.1103/PhysRevLett.87.215502

  View details for Web of Science ID 000172400600026

  View details for PubMedID 11736348

• Bioassay of prostate-specific antigen (PSA) using microcantilevers NATURE BIOTECHNOLOGY Wu, G. H., Datar, R. H., Hansen, K. M., Thundat, T., Cote, R. J., Majumdar, A. 2001; 19 (9): 856-860

  Abstract

  Diagnosis and monitoring of complex diseases such as cancer require quantitative detection of multiple proteins. Recent work has shown that when specific biomolecular binding occurs on one surface of a microcantilever beam, intermolecular nanomechanics bend the cantilever, which can be optically detected. Although this label-free technique readily lends itself to formation of microcantilever arrays, what has remained unclear is the technologically critical issue of whether it is sufficiently specific and sensitive to detect disease-related proteins at clinically relevant conditions and concentrations. As an example, we report here that microcantilevers of different geometries have been used to detect two forms of prostate-specific antigen (PSA) over a wide range of concentrations from 0.2 ng/ml to 60 microg/ml in a background of human serum albumin (HSA) and human plasminogen (HP) at 1 mg/ml, making this a clinically relevant diagnostic technique for prostate cancer. Because cantilever motion originates from the free-energy change induced by specific biomolecular binding, this technique may offer a common platform for high-throughput label-free analysis of protein-protein binding, DNA hybridization, and DNA-protein interactions, as well as drug discovery.

  View details for Web of Science ID 000170774000025

  View details for PubMedID 11533645

• Scanning thermal microscopy ANNUAL REVIEW OF MATERIALS SCIENCE Majumdar, A. 1999; 29: 505-585

  View details for Web of Science ID 000082534400016

• MICROSCALE HEAT-CONDUCTION IN DIELECTRIC THIN-FILMS JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME Majumdar, A. 1993; 115 (1): 7-16

  View details for Web of Science ID A1993KP91000002

• FRACTAL MODEL OF ELASTIC-PLASTIC CONTACT BETWEEN ROUGH SURFACES JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME Majumdar, A., BHUSHAN, B. 1991; 113 (1): 1-11

  View details for Web of Science ID A1991FE82200001