Yi-Yan Wang

Resistivity plateau and extremely large magnetoresistance in NbAs 2 and TaAs 2

In topological insulators (TIs), metallic surface conductance saturates the insulating bulk resistance with de- creasing temperature, resulting in resistivity plateau at low temperatures as a transport signature originating from metallic surface modes protected by time reversal symmetry (TRS). Such characteristic has been found in several materials including Bi2Te2Se, SmB6 etc. Recently, similar behavior has been observed in metallic com- pound LaSb, accompanying an extremely large magetoresistance (XMR). Shubnikov-de Hass (SdH) oscillation at low temperatures further confirms the metallic behavior of plateau region under magnetic fields. LaSb[1] has been proposed by the authors as a possible topological semimetal (TSM), while negative magnetoresistance is absent at this moment. Here, high quality single crystals of NbAs2/TaAs2 with inversion symmetry have been grown and the resistivity under magnetic field is systematically investigated. Both of them exhibit metallic behavior under zero magnetic field, and a metal-to-insulator transition occurs when a nonzero magnetic field is applied, resulting in XMR (1.0*105% for NbAs2 and 7.3*105% for TaAs2 at 2.5 K & 14 T). With tempera- ture decreased, a resistivity plateau emerges after the insulator-like regime and SdH oscillation has also been observed in NbAs2 and TaAs2.

Magnetoresistance and Shubnikov-de Haas oscillation in YSb

YSb crystals are grown and the transport properties under magnetic field are measured. The resistivity exhibits metallic behavior under zero magnetic field and the low-temperature resistivity shows a clear upturn once a moderate magnetic field is applied. The upturn is greatly enhanced by increasing magnetic field. At low temperature (2.5 K) and high field (14 T), the transverse magnetoresistance (MR) is quite large . In addition, the Shubnikov-de Haas (SdH) oscillation has also been observed in YSb. The possible trivial Berry phase extracted from the SdH oscillation, the band structure revealed by angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations demonstrate that YSb is a topologically trivial material. The extremely large MR (XMR) in YSb may originate from the electron-hole compensation.

Large linear magnetoresistance in a new Dirac material BaMnBi2

We report the synthesis of high quality single crystals of BaMnBi2 and investigate the transport properties of the samples. The Hall data reveals electron-type carriers and a mobility mu(5K) =1500cm2/Vs. The temperature dependence of magnetization displays behavior that is different from CaMnBi2 or SrMnBi2 , which suggests the possible different magnetic structure of BaMnBi2. Angle-dependent magnetoresistance reveals the quasi-two-dimensional Fermi surface. A crossover from semiclassical MR-H2 dependence in low field to MR-H dependence in high field is observed in transverse magnetoresistance. Our results indicate the anisotropic Dirac fermion states in BaMnBi2.

Magneto-transport and electronic structures of BaZnBi2

We report the magneto-transport properties and electronic structures of BaZnBi2. BaZnBi2 is a quasi-two-dimensional material with metallic behavior. Transverse magnetoresistance (MR) depends on magnetic field linearly and exhibits Shubnikov–de Haas (SdH) oscillation at low temperature and high field. The observed linear MR may originate from the disorder in samples or the edge conductivity in compensated two-component systems. The first-principles calculations reveal the absence of stable gapless Dirac fermion. Combined with the trivial Berry phase extracted from the SdH oscillation, BaZnBi2 is suggested as a topologically trivial semimetal. Nearly compensated electron-like Fermi surfaces (FSs) and hole-like FSs coexist in BaZnBi2.

Raman scattering study of large magnetoresistance semimetals TaAs 2 and NbAs 2

We have performed polarized and temperature-dependent Raman scattering measurements on extremely large magnetoresistance compounds

Effects of vanadium doping on BaFe2As2

{\mathrm{TaAs}}_{2}

Crystal growth and magneto-transport properties of α-ZrSb2 and α-HfSb2

and

Low-temperature properties of β-MoTe2 grown by the chemical vapor transport method

{\mathrm{NbAs}}_{2}

Facile synthesis of size tunable Fe3O4 nanoparticles in bisolvent system

. In both crystals, all the Raman active modes, including six

Extremely large magnetoresistance and electronic structure of TmSb

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