Jiayue Wang

All Publications

• Atomic-Scale Moiré and Electronic Structure Analysis of Twisted Epitaxial MoS2-Au-MoS2 Heterostructures. Nano letters Cui, Y., Xu, K., Ren, P., Yuan, L., Czaja, P., Barnum, A., Sarkar, P., Altman, A., Bustillo, K., Kundu, S., Ramdas, A., Wang, X., Wan, G., Wang, Y., Wang, J., Song, C., Lim, C., Zheng, Q., Yao, H., Heinz, T., Hwang, H. Y., Majumdar, A., Dionne, J. A., Ophus, C., da Jornada, F. H., Sinclair, R., Cui, Y. 2026

  Abstract

  Twisted epitaxy enables precise orientation control of nanostructures confined within van der Waals (vdW) gaps. Here, we investigate the moiré and electronic structure of a representative twisted epitaxial system, where Au nanodiscs are grown inside twisted bilayer MoS2 with a 6° interlayer twist, inducing a 3° symmetrical misalignment of Au relative to each MoS2 layer (MoS2-Au-MoS2). Using multislice electron ptychography (MEP), we resolve the three-dimensional "moiré-of-moirés" structure of MoS2-Au-MoS2 with atomic resolution. Electron energy loss spectroscopy (EELS) shows that MoS2 encapsulation significantly reduces the plasmon energy of Au nanodiscs compared with their unencapsulated counterparts. Furthermore, first-principles calculations reveal that Au insertion alters the electronic band alignment near the Fermi level of bilayer MoS2. Our results introduce a twisted MoS2-Au-MoS2 heterostructure as a structurally and electronically rich material system and establish twisted epitaxy as a new strategy for moiré engineering and the synthesis of 2D-confined materials with tunable optoelectronic properties.

  View details for DOI 10.1021/acs.nanolett.5c04205

  View details for PubMedID 41705938

• Reducing the Strain Required for Ambient-Pressure Superconductivity in Ruddlesden-Popper Bilayer Nickelates. Advanced materials (Deerfield Beach, Fla.) Tarn, Y., Liu, Y., Theuss, F., Li, J., Wang, B. Y., Bhatt, L., Wang, J., Song, J., Thampy, V., Goodge, B. H., Muller, D. A., Shen, Z. X., Yu, Y., Hwang, H. Y. 2026: e20724

  Abstract

  The discovery of high-temperature superconductivity in pressurized bulk Ruddlesden-Popper (RP) bilayer nickelates has prompted the conjecture that epitaxial compressive strain might mimic essential aspects of hydrostatic pressure. The realization of superconductivity in films on SrLaAlO4 (001) (SLAO) supports this correspondence, yet it remains unclear whether the pressure-temperature phase diagram of RP bilayer nickelates can be systematically mapped (and studied at ambient pressure) as a function of epitaxial strain. To this end, experimental access near the elusive edge of the superconducting phase boundary would provide invaluable insight into the nature of the superconducting state and the ground state from which it emerges. Here we report superconducting RP bilayer nickelates grown on LaAlO3 (001) (LAO), where the compressive strain required for ambient-pressure superconductivity is nearly halved to -1.2%. These films exhibit a superconducting onset above 10 K and reach zero resistance at 3 K, with normal-state transport properties differing from those of films grown on SLAO. Our comparative study shows that strain-rather than interfacial structure is the primary factor governing the superconductivity and normal-state properties. This work offers a new opportunity to probe emergent phenomena near the superconducting phase boundary in the strain-temperature phase diagram of RP bilayer nickelates.

  View details for DOI 10.1002/adma.202520724

  View details for PubMedID 41677074

• Freestanding SrNbO₃ membranes as flexible transparent conductors APL MATERIALS Ko, E., Wang, B., Lee, J., Wang, J., Crust, K. J., Hwang, H. Y. 2026; 14 (1)

  View details for DOI 10.1063/5.0310409

  View details for Web of Science ID 001653970300001

• Strain-induced lead-free morphotropic phase boundary. Nature communications Ghanbari, R., Kp, H., Patel, K., Zhou, H., Zhou, T., Liu, R., Wu, L., Khandelwal, A., Crust, K. J., Hazra, S., Carroll, J., Meyers, C. J., Wang, J., Prosandeev, S., Qiao, H., Kim, Y. H., Nabei, Y., Chi, M., Sun, D., Balke, N., Holt, M., Gopalan, V., Spanier, J. E., Muller, D. A., Bellaiche, L., Hwang, H. Y., Xu, R. 2025; 16 (1): 7766

  Abstract

  Enhanced susceptibilities in ferroelectrics often arise near phase boundaries between competing ground states. While chemically-induced phase boundaries have enabled ultrahigh electrical and electromechanical responses in lead-based ferroelectrics, precise chemical tuning in lead-free alternatives, such as (K,Na)NbO3 thin films, remains challenging due to the high volatility of alkali metals. Here, we demonstrate strain-induced morphotropic phase boundary-like polymorphic nanodomain structures in chemically simple, lead-free, epitaxial NaNbO3 thin films. Combining ab initio simulations, thin-film epitaxy, scanning probe microscopy, synchrotron X-ray diffraction, and electron ptychography, we reveal a labyrinthine structure comprising coexisting monoclinic and bridging triclinic phases near a strain-induced phase boundary. The coexistence of energetically competing phases facilitates field-driven polarization rotation and phase transitions, giving rise to a multi-state polarization switching pathway and large enhancements in dielectric susceptibility and tunability across a broad frequency range. Our results open new possibilities for engineering lead-free thin films with enhanced functionalities for next-generation applications.

  View details for DOI 10.1038/s41467-025-63041-w

  View details for PubMedID 40835605

  View details for PubMedCentralID 8423788

• Fermi Level Equilibration and Charge Transfer at the Exsolved Metal-Oxide Interface. Journal of the American Chemical Society Wang, J., Yang, J., Wardini, J. L., Waluyo, I., Hunt, A., Crumlin, E. J., Fairley, N., Bowman, W. J., Hwang, H. Y., Yildiz, B. 2025

  Abstract

  Exsolution is a promising approach for fabricating oxide-supported metal nanocatalysts through redox-driven metal precipitation. A defining feature of exsolved nanocatalysts is their anchored metal-oxide interface, which exhibits exceptional structural stability in (electro)catalysis. However, the electronic interactions at this unique interface remain unclear, despite their known impact on catalytic performance. In this study, we confirm charge transfer between the host oxide and the exsolved metal by demonstrating a two-stage Fermi level (EF) evolution on SrTi0.65Fe0.35O3-δ (STF) during metallic iron (Fe0) exsolution. Combining ambient pressure X-ray photoelectron spectroscopy with theoretical analysis, we show that EF initially rises due to electron doping from oxygen vacancy formation in STF. Subsequently, upon Fe0 precipitation, EF stabilizes and becomes insensitive to further oxygen release in STF, driven by EF equilibration and charge transfer between STF and the exsolved Fe0. These findings highlight the importance of considering electronic metal-support interactions when optimizing exsolved nanocatalysts.

  View details for DOI 10.1021/jacs.4c14695

  View details for PubMedID 39818799

• Molecular H2as the Reducing Agent in Low-Temperature Oxide Reduction Using Calcium Hydride. Journal of the American Chemical Society Wang, J., Yu, Y., Abdelkawy, A., Li, J., Li, J., Yang, J., Ko, E. K., Lee, Y., Thampy, V., Cui, Y., Todorova, M., Neugebauer, J., Hwang, H. Y. 2025

  Abstract

  Low-temperature synthesis is crucial for advancing sustainable manufacturing and accessing novel metastable phases. Metal hydrides have shown great potential in facilitating the reduction of oxides at low temperatures, yet the underlying mechanism─whether driven by H-, H2, or atomic H─remains unclear. In this study, we employ in situ electrical transport measurements and first-principles calculations to investigate the CaH2-driven reduction kinetics in epitaxial alpha-Fe2O3 thin films. Intriguingly, samples in direct contact with or separated from CaH2 powders exhibit similar apparent activation energies for H2 reduction, although direct contact significantly increases the reduction rate. These findings indicate that molecular H2 is the dominant reducing species in the low-temperature reduction of oxides using CaH2, with a key aspect of the hydrides' superior reducing power attributed to their ability to eliminate residual moisture. This work underscores the critical role of moisture control in enabling effective low-temperature oxide reduction for advanced material synthesis.

  View details for DOI 10.1021/jacs.4c17825

  View details for PubMedID 39807810

• Recommended strategies for quantifying oxygen vacancies with X-ray photoelectron spectroscopy JOURNAL OF THE EUROPEAN CERAMIC SOCIETY Wang, J., Mueller, D. N., Crumlin, E. J. 2024; 44 (15)

  View details for DOI 10.1016/j.jeurceramsoc.2024.116709

  View details for Web of Science ID 001275754400001