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Fu, Huixia

Publications and source records attributed to Fu, Huixia.

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Coexistence of Dirac fermion and charge density wave in the square-net-based semimetal LaAuSb 2

Here, we report a comprehensive study of magnetotransport properties, angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) calculations on self-flux grown LaAuSb 2 single crystals. Resistivity and Hall measurements reveal a charge density wave (CDW) transition at 77 K. MR and de Haas-Van Alphen (dHvA) measurements indicate that the transport properties of LaAuSb 2 are dominated by Dirac fermions that arise from Sb square nets. ARPES measurements and DFT calculations reveal an electronic structure with a common feature of the square-net-based topological semimetals, which is in good agreement with the magnetotransport properties. Our results indicate the coexistence of CDW and Dirac fermion in LaAuSb 2 , both of which are linked to the bands arising from the Sb-square net, suggesting that the square net could serve as a structural motif to explore various electronic orders.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Induced anomalous Hall effect of massive Dirac fermionsin ZrTe 5 and HfTe 5 thin flakes

Research on the anomalous Hall effect (AHE) has been lasting for a century to make clear the underlying physical mechanism. Generally, the AHE appears in magnetic materials, in which the extrinsic process related to scattering effects and intrinsic contribution connected with Berry curvature are crucial. Recently, AHE has been counterintuitively observed in nonmagnetic topological materials and attributed to the existence of Weyl points. However, the Weyl point scenario would lead to unsaturated AHE even in large magnetic fields and contradicts the saturation of AHE in several tesla (T) in experiments. In this work, we investigate the Hall effect of ZrTe 5 and HfTe 5 thin flakes in static ultrahigh magnetic fields up to 33 T. We find the AHE saturates to 55(70)Ω 1 cm 1 for ZrTe 5 (HfTe 5 ) thin flakes above ~10T. Combining detailed magnetotransport experiments and Berry curvature calculations, we clarify that the splitting of massive Dirac bands without Weyl points can be responsible for AHE in nonmagnetic topological materials ZrTe 5 and HfTe 5 thin flakes. This model can identify our thin flake samples to be weak topological insulators and serve as a tool to probe the band structure topology in topological materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

A native oxide high-κ gate dielectric for two-dimensional electronics

Silicon-based transistors are approaching their physical limits and thus new high-mobility semiconductors are sought to replace silicon in the microelectronics industry. Both bulk materials (such as silicon-germanium and III–V semiconductors) and low-dimensional nanomaterials (such as one-dimensional carbon nanotubes and two-dimensional transition metal dichalcogenides) have been explored, but, unlike silicon, which uses silicon dioxide (SiO 2 ) as its gate dielectric, these materials suffer from the absence of a high-quality native oxide as a dielectric counterpart. This can lead to compatibility problems in practical devices. Here, we show that an atomically thin gate dielectric of bismuth selenite (Bi 2 SeO 5 ) can be conformally formed via layer-by-layer oxidization of an underlying high-mobility two-dimensional semiconductor, Bi 2 O 2 Se. Using this native oxide dielectric, high-performance Bi 2 O 2 Se field-effect transistors can be created, as well as inverter circuits that exhibit a large voltage gain (as high as 150). The high dielectric constant (~21) of Bi 2 SeO 5 allows its equivalent oxide thickness to be reduced to 0.9 nm while maintaining a gate leakage lower than thermal SiO 2 . The Bi 2 SeO 5 can also be selectively etched away by a wet chemical method that leaves the mobility of the underlying Bi 2 O 2 Se semiconductor almost unchanged.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗