All Publications

  • Size-Induced Ferroelectricity in Antiferroelectric Oxide Membranes. Advanced materials (Deerfield Beach, Fla.) Xu, R., Crust, K. J., Harbola, V., Arras, R., Patel, K. Y., Prosandeev, S., Cao, H., Shao, Y. T., Behera, P., Caretta, L., Kim, W. J., Khandelwal, A., Acharya, M., Wang, M. M., Liu, Y., Barnard, E. S., Raja, A., Martin, L. W., Gu, X. W., Zhou, H., Ramesh, R., Muller, D. A., Bellaiche, L., Hwang, H. Y. 2023: e2210562


    Despite extensive studies on size effects in ferroelectrics, how structures and properties evolve in antiferroelectrics with reduced dimensions still remains elusive. Given the enormous potential of utilizing antiferroelectrics for high energy-density storage applications, understanding their size effects would provide key information for optimizing device performances at small scales. Here, we investigate the fundamental intrinsic size dependence of antiferroelectricity in lead-free NaNbO3 membranes. Via a wide range of experimental and theoretical approaches, we probe an intriguing antiferroelectric-to-ferroelectric transition upon reducing membrane thickness. This size effect leads to a ferroelectric single-phase below 40 nm as well as a mixed-phase state with ferroelectric and antiferroelectric orders coexisting above this critical thickness. Furthermore, we show that the antiferroelectric and ferroelectric orders are electrically switchable. First-principle calculations further reveal the observed transition is driven by the structural distortion arising from the membrane surface. Our work provides direct experimental evidence for intrinsic size-driven scaling in antiferroelectrics and demonstrates enormous potential of utilizing size effects to drive emergent properties in environmentally benign lead-free oxides with the membrane platform. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202210562

    View details for PubMedID 36739113

  • Coupled harmonic oscillator models for correlated plasmons in one-dimensional and quasi-one-dimensional systems. Journal of physics. Condensed matter : an Institute of Physics journal Khandelwal, A., Mohammad Tashrif, S., Rusydi, A. 2021


    A new phenomenon of correlated plasmons was first observed in the insulating phase of the Sr1-xNb1-yO3+ family [T. C. Asamara et al., Nat Commun 8, 15271 (2017)]. The correlated plasmons are tunable, have multiple plasmonic frequencies, and exhibit low loss - making them desirable in numerous plasmonic applications. However, their fundamental mechanism is yet to be explored. While conventional plasmons can be understood solely by considering long-range interactions, unconventional correlated plasmons arise in correlated electron systems and require consideration of the short-range interactions. Here, we report how the interplay of short-range and long-range interactions determines the correlated plasmon phenomena through a coupled harmonic oscillator model of both 1D and quasi-1D systems. In each system, the impact of various physical parameters like the number of oscillators, energy scale, free electron scattering parameter, quasi-particle concentration, charges, effective masses, and Coulomb interaction strengths are explored to gain an understanding of their impact on the complex dielectric function and loss function. We study both cases where the parameters are the same for all quasi-particles and where effective mass, Coulomb interaction strength, and charge are varied for individual quasi-particles. In an extended model of the quasi-1D system, we study both cases where the rung symmetry of all parameters is conserved and where it is broken. When rung symmetry is conserved, the overall trends in optical and plasmonic peaks are the same as the 1D model, though the peaks tend to shift to higher energies and amplitudes. When rung symmetry is broken, the quasi-1D behavior deviates significantly from the 1D model, including an increase in the maximum possible number of optical and plasmonic peaks. Overall, our results demonstrate the significance of the interplay of short-range and long-range interactions in determining the correlated plasmons and identifying how various parameters can be used to tune the resulting plasmons.

    View details for DOI 10.1088/1361-648X/ac19e4

    View details for PubMedID 34340220

  • Correlated cation lattice symmetry and oxygen octahedral rotation in perovskite oxide heterostructures JOURNAL OF APPLIED PHYSICS Chen, P. F., Lan, D., Liu, C., Wu, X. H., Khandelwal, A., Li, M. S., Li, C. J., Yang, P., Yu, X. J., Chen, J. S., Pennycook, S. J., Ariando, A., Huang, Z., Chow, G. M. 2021; 129 (2)

    View details for DOI 10.1063/5.0035501

    View details for Web of Science ID 000608037900003

  • A cost-effective quantum eraser demonstration Physics Education Khandelwal, A., Tan, J., Leong, T., Yang, Y., Venkatesan, T., Jani, H. 2021; 56 (3): 033007

    View details for DOI 10.1088/1361-6552/abea49

  • Using demonstrations to explain abstract science concepts: Hands-on and online demonstration-based pedagogy for enhancing student engagement in physics. Jani, H., Khandelwal, A., Leong, T., Yang, Y., Venkatesan, T. National Institute of Education (Singapore). Singapore. 2020 ; Research Brief Series (2010-3093): 20-018