arXiv subjects

Wenhai Song

Publications and source records attributed to Wenhai Song.

5 recordsLinked to original sources

arXiv2025

Anisotropy of linear magnetoresistance in Kagome metal ZrV$_6$Sn$_6$

The Kagome lattice has attracted extensive attention due to the diverse magnetic properties and non-trivial electronic states generated by its unique atomic arrangement, which provides an excellent system for exploring macroscopic quantum behavior. Here, we report the anomalous transport properties in 166-type Kagome metal ZrV$_6$Sn$_6$ single crystals. The quadratic and linear magnetoresistance (LMR) can be observed depending on the directions of the field and the current. Integrating Hall resistivity and quantum oscillation measurements, we found that the LMR could match well with the Abrikosov model. However, this model encounters difficulties in explaining the anisotropy of the magnetoresistance. To solve the issue, we extrapolate the Abrikosov model to the case of two-dimensional linear dispersion. It was found that when the field is parallel to the linear dependence momentum, the quantized energy is $\epsilon_n^{\pm}$ = $\pm v\sqrt{p^2+2eHn/c}$, resulting in LMR. By contrast, when it is parallel to the non-linear dependence momentum, the energy is $\epsilon_n^{\pm}$ = $\pm v\sqrt{2eHn/c}$, without yielding LMR. Through the combination of experiment and theory, the modified Abrikosov model could interpret the macroscopic quantum transport in ZrV$_6$Sn$_6$ crystal. The present research provides a new perspective for understanding the LMR behavior.

cond-mat.str-el↗

arXiv2022

A phase transition driven by subtle distortion without broken symmetry on spin, charge and lattice in Layered LnCu4-δP2(Ln=Eu, Sr)

In the scenario of Landau phase transition theory in condensed matter physics, any thermal dynamic phase transition must be subject to some kind of broken symmetries, that are relative to its spin, charge, orbital and lattice. Here we report a rare phase transition at Tp ~120 K or 140 K in layered materials LnCu4-δP2 (Ln=Eu, Sr) driven by a subtle structural-distortion without any broken symmetry on charge, spin and lattice. The variations of the lattice parameters, (ΔLc/Lc) ~ 0.013% or 0.062%, verified by thermal expansion, is much less than that for a typical crystalline phase transition (~0.5-1%), but the significant anomaly in heat capacity provides clear evidence of its intrinsic nature of thermodynamic transition.

cond-mat.str-el↗

arXiv2021

The power of flexible lattice in Ca3Ru2O7: Exquisite control of the electrical transport via anisotropic magnetostriction

Ca3Ru2O7 is a correlated and spin-orbit-coupled system with an extraordinary anisotropy. It is both interesting and unique largely because this material exhibits conflicting phenomena that are often utterly inconsistent with traditional precedents, particularly, the quantum oscillations in the nonmetallic state and colossal magnetoresistivity achieved by avoiding a fully spin-polarized state. This work focuses on the relationship between the lattice and transport properties along each crystalline axis and reveals that application of magnetic field, H, along different crystalline axes readily stretches or shrinks the lattice in a uniaxial manner, resulting in distinct electronic states. Furthermore, application of modest pressure drastically amplifies the anisotropic magnetoelastic effect, leading to either an occurrence of a robust metallic state at H || hard axis or a reentrance of the nonmetallic state at H || easy axis. Ca3Ru2O7 presents a rare lattice-dependent magnetotransport mechanism, in which the extraordinary lattice flexibility enables an exquisite control of the electronic state via magnetically stretching or shrinking the crystalline axes, and the spin polarization plays an unconventional role unfavorable for maximizing conductivity. At the heart of the intriguing physics is the anisotropic magnetostriction that leads to exotic states.

cond-mat.str-el↗

arXiv2015

Giant negative thermal expansion covering room temperature in nanocrystalline GaNxMn3

Materials with negative thermal expansion (NTE), which contract upon heating, are of great interest both technically and fundamentally. Here, we report giant NTE covering room temperature in mechanically milled antiperovksite GaNxMn3 compounds. The micrograin GaNxMn3 exhibits a large volume contraction at the antiferromagnetic (AFM) to paramagnetic (PM) (AFM-PM) transition within a temperature window (ΔT) of only a few kelvins. The grain size reduces to ~ 30 nm after slight milling, while ΔT is broadened to 50K. The corresponding coefficient of linear thermal expansion (α) reaches ~ -70 ppm/K, which is almost two times larger than those obtained in chemically doped antiperovskite compounds. Further reducing grain size to ~ 10 nm, ΔT exceeds 100 K and α remains as large as -30 ppm/K (-21 ppm/K) for x = 1.0 (x = 0.9). Excess atomic displacements together with the reduced structural coherence, revealed by high-energy X-ray pair distribution functions, are suggested to delay the AFM-PM transition. By controlling the grain size via mechanically alloying or grinding, giant NTE may also be achievable in other materials with large lattice contraction due to electronic or magnetic phase transitions.

cond-mat.mtrl-sci↗

arXiv2013

New Superconductivity in Layered 1T-TaS2-xSex Single Crystals Fabricated by Chemical Vapor Transport

Layered transition-metal dichalcogenides 1T-TaS2-xSex (0<=x<=2) single crystals have been successfully fabricated by using a chemical vapor transport technique in which Ta locates in octahedral coordination with S and Se atoms. This is the first superconducting example by the substitution of S site, which violates an initial rule based on the fact that superconductivity merely emerges in 1T-TaS2 by applying the high pressure or substitution of Ta site. We demonstrate the appearance of a series of electronic states in 1T-TaS2-xSex with Se content. Namely, the Mott phase melts into a nearly commensurate charge-density-wave (NCCDW) phase, superconductivity in a wide x range develops within the NCCDW state, and finally commensurate charge-density-wave (CCDW) phase reproduces for heavy Se content. The present results reveal that superconductivity is only characterized by robust Ta 5d band, demonstrating the universal nature in 1T-TaS2 systems that superconductivity and NCCDW phase coexist in the real space.

cond-mat.supr-con↗