arXiv subjects

D. D. Liang

Publications and source records attributed to D. D. Liang.

5 recordsLinked to original sources

arXiv2019

Current jetting distorted planar Hall effect in a Weyl semimetal with ultrahigh mobility

A giant planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) is observed in TaP, a nonmagnetic Weyl semimetal with ultrahigh mobility. The perpendicular resistivity (i.e., the planar magnetic field applied normal to the current) far exceeds the zero-field resistivity, which thus rules out the possible origin of negative longitudinal magnetoresistance. The giant PHE/AMR is finally attributed to the large anisotropic orbital magnetoresistance that stems from the ultrahigh mobility. Furthermore, the mobility-enhanced current jetting effects are found to strongly deform the line shape of the curves, and their evolution with the changing magnetic field and temperature is also studied. Although the giant PHE/AMR suggests promising applications in spintronics, the enhanced current jetting shows the other side of the coin, which needs to be considered in the future device design.

cond-mat.mtrl-sci↗

arXiv2018

Origin of planar Hall effect in type-II Weyl semimetal MoTe2

Besides the negative longitudinal magnetoresistance (MR), planar Hall effect (PHE) is a newly emerging experimental tool to test the chiral anomaly or nontrivial Berry curvature in Weyl semimetals (WSMs). However, the origins of PHE in various systems are not fully distinguished and understood. Here we perform a systematic study on the PHE and anisotropic MR (AMR) of Td-MoTe2, a type-II WSM. Although the PHE and AMR curves can be well fitted by the theoretical formulas, we demonstrate that the anisotropic resistivity arises from the orbital MR (OMR), instead of the negative MR as expected in the chiral anomaly effect. In contrast, the absence of negative MR indicates that the large OMR dominates over the chiral anomaly effect. This explains why it is difficult to measure negative MR in type-II WSMs. We argue that the measured PHE can be related with the chiral anomaly only when the negative MR is simultaneously observed.

cond-mat.mtrl-sci↗

arXiv2018

Extreme magnetoresistance and Shubnikov-de Haas oscillations in ferromagnetic DySb

The electronic structures of a representative rare earth monopnictide (i.e., DySb) under high magnetic field (i.e., in the ferromagnetic state) are studied from both experimental and theoretical aspects. A non-saturated extremely large positive magnetoresistance (XMR) is observed (as large as 3.7*10^4% at 1.8 K and 38.7 T), along with the Shubnikov-de Haas oscillations that are well reproduced by our first principles calculations. Three possible origins of XMR are examined. Although a band inversion is found theoretically, suggesting that DySb might be topologically nontrivial, it is deeply underneath the Fermi level, which rules out a topological nature of the XMR. The total densities of electron-like and hole-like carriers are not fully compensated, showing that compensation is unlikely to account for the XMR. The XMR is eventually understood in terms of high mobility that is associated with the steep linear bands. This discovery is important to the intensive studies on the XMR of rare earth monopnictides.

cond-mat.mtrl-sci↗

arXiv2018

Non-stoichiometry effects on the extreme magnetoresistance in Weyl semimetal WTe2

Non-stoichiometry effect on the extreme magnetoresistance is systematically investigated for the Weyl semimetal WTe2. Magnetoresistance and Hall resistivity are measured for the as-grown samples with a slight difference in Te vacancies and the annealed samples with increased Te vacancies. The fittings to a two-carrier model show that the magnetoresistance is strongly dependent on the residual resistivity ratio (i.e., the degree of non-stoichiometry), which is eventually understood in terms of electron doping which not only breaks the balance between electron-type and hole-type carrier densities but also reduces the average carrier mobility. Thus, compensation effect and ultrahigh mobility are probably the main driving force of the extreme magnetoresistance in WTe2.

cond-mat.mtrl-sci↗

arXiv2018

Planar Hall effect in type-II Weyl semimetal WTe2

Adler-Bell-Jackiw chiral anomaly is a representative feature arising from the topological nature in topological semimetal. We report the first experimental observation of giant planar Hall effect in type-II Weyl semimetal WTe2. Our comprehensive analyes of the experimental data demonstrate that the detected planar Hall effect is originated from the chiral anomaly of Weyl fermions. Unlike the somewhat elusive negative magnetoresistance, the planar Hall effect is robust and easy to be detected in type-II Weyl semimetal. This work reveals that the planar Hall effect is an effective transport probe to determine the topological nature of topological semimetals, especially in type-II Weyl semimetals.

cond-mat.mtrl-sci↗