arXiv subjects

Yongcheng Liang

Publications and source records attributed to Yongcheng Liang.

4 recordsLinked to original sources

arXiv2019

Pressure-driven switching of magnetism in layered CrCl3

Layered transition-metal compounds with controllable magnetic behaviors provide many fascinating opportunities for the fabrication of high-performance magneto-electric and spintronic devices. The tuning of their electronic and magnetic properties is usually limited to the change of layer thickness, electrostatic doping, and the control of electric and magnetic fields. However, pressure has been rarely exploited as a control parameter for tailoring their magneto-electric properties. Here, we report a unique pressure-driven isostructural phase transition in layered CrCl3 accompanied by a simultaneous switching of magnetism from a ferromagnetic to an antiferromagnetic ordering. Our experiments, in combination with ab initio calculations, demonstrate that such a magnetic transformation hinders the band-gap collapse under pressure, leading to an anomalous semiconductor-to-semiconductor transition. Our findings not only reveal high potential of CrCl3 in electronic and spintronic applications under ambient and extreme conditions but also establish the basis for exploring unusual phase transitions in layered transition-metal compounds.

cond-mat.mtrl-sci↗

arXiv2019

Identification of a monoclinic metallic state in VO2 from a modified first-principles approach

Metal-insulator transition underlies many remarkable and technologically important phenomena in VO2. Even though its monoclinic structure had before been the reserve of the insulating state, recent experiments have observed an unexpected monoclinic metallic state. Here we use a modified approach combining first-principles calculations with orbital-biased potentials to reproduce the correct stability ordering and electronic structure of different phases of VO2. We identify a ferromagnetic monoclinic metal that is likely to be the experimentally observed mysterious metastable state. Furthermore, our calculations show that an isostructural insulator-metal electronic transition is followed by the lattice distortion from the monoclinic structure to the rutile structure. These results not only explain the experimental observations of the monoclinic metallic state and the decoupled structural and electronic transitions of VO2, but also provide a understanding for the metal-insulator transition in other strongly correlated d electron systems.

cond-mat.str-el↗

arXiv2012

Novel Tungsten Triboride

A highly stable tungsten triboride with the Pearson symbol hP24 (hP24-WB3) is identified by using density functional theory calculations. This new structure can be derived from the well-known hP3 configuration by removing one third of tungsten atoms systematically so that the remaining tungsten atoms form three cycled layers of open hexagons with each a layer displaced by one atom. Such a porous and metallic system has an unexpectedly high Vickers hardness of 38.3 GPa. It is revealed that a three-dimensional covalent framework composed of hexagonal boron planes interconnected with strong zigzag W-B bonds is responsible for its unusual high hardness.

cond-mat.mtrl-sci↗

arXiv2007

Theoretical Evidence for the Berry-Phase Mechanism of Anomalous Hall Transport: First-principles Studies on CuCr$_2$Se$_{4-x}$Br$_x$

To justify the origin of anomalous Hall effect (AHE), it is highly desirable to have the system parameters tuned continuously. By quantitative calculations, we show that the doping dependent sign reversal in CuCr$_{2}$Se$_{4-x}$Br$_{x}$, observed but not understood, is nothing but direct evidence for the Berry-Phase mechanism of AHE. The systematic calculations well explain the experiment data for the whole doping range where the impurity scattering rates is changed by several orders with Br substitution. Further sign change is also predicted, which may be tested by future experiments.

cond-mat.mes-hall↗