Emerging weak antilocalization effect in Ta0.7Nb0.3Sb2 semimetal single crystals

doi:10.1007/s11467-022-1198-6

Front. Phys.

2023, Vol. 18

Issue (1) : 13304 https://doi.org/10.1007/s11467-022-1198-6

RESEARCH ARTICLE

Emerging weak antilocalization effect in Ta_0.7Nb_0.3Sb₂semimetal single crystals

Meng Xu^1,², Lei Guo²(

), Lei Chen³, Ying Zhang⁴, Shuang-Shuang Li⁴, Weiyao Zhao⁵(

), Xiaolin Wang⁶, Shuai Dong², Ren-Kui Zheng⁴(

)

¹. College of Science, Hohai University, Nanjing 210098, China
². School of Physics, Southeast University, Nanjing 211189, China
³. School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
⁴. School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, China
⁵. Department of Materials Science & Engineering, Monash University, Clayton 3800 VIC, Australia
⁶. Institute for Superconducting and Electronic Materials, & ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Innovation Campus, University of Wollongong, North Wollongong NSW 2500, Australia

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Abstract

Weak antilocalization (WAL) effect is commonly observed in low-dimensional systems, three-dimensional (3D) topological insulators and semimetals. Here, we report the growth of high-quality Ta_0.7Nb_0.3Sb₂ single crystals via the chemical vapor transport (CVT). Clear sign of the WAL effect is observed below 50 K, probably due to the strong spin−orbital coupling in 3D bulk. In addition, it is worth noting that a relatively large MR of 120% appears under 1 T magnetic field at T = 2 K. Hall measurements and two-band model fitting results reveal high carrier mobility (>1000 cm²·V⁻¹·s⁻¹ in 2–300 K region), and off-compensation electron/hole ratio of ~8:1. Due to the angular dependence of the WAL effect and the fermiology of the Ta_0.7Nb_0.3Sb₂ crystals, interesting magnetic-field-induced changes of the symmetry of the anisotropic magnetoresistance (MR) from two-fold (≤ 0.6 T) to four-fold (0.8–1.5 T) and finally to two-fold (≥ 2 T) are observed. This phenomenon is attributed to the mechanism shift from the low-field WAL dominated MR to WAL and fermiology co-dominated MR and finally to high-field fermiology dominated MR. All these signs indicate that Ta_0.7Nb_0.3Sb₂ may be a topological semimetal candidate, and these magnetotransport properties may attract more theoretical and experimental exploration of the (Ta,Nb)Sb₂ family.

Keywords topological semimetal magnetoresistance weak antilocalization effect spin−orbital coupling

Corresponding Author(s): Lei Guo,Weiyao Zhao,Ren-Kui Zheng

Issue Date: 30 November 2022

Cite this article:

Meng Xu,Lei Guo,Lei Chen, et al. Emerging weak antilocalization effect in Ta_0.7Nb_0.3Sb₂semimetal single crystals[J]. Front. Phys. , 2023, 18(1): 13304.

URL:

https://academic.hep.com.cn/fop/EN/10.1007/s11467-022-1198-6
https://academic.hep.com.cn/fop/EN/Y2023/V18/I1/13304

Fig.1 (a) XRD pattern of the Ta_0.7Nb_0.3Sb₂ single crystal. Inset: An optical image of the crystal. (b) XRD rocking curve taken on the (

4 ¯ 02

) diffraction peak. (c−g) The element spectrum and element mapping patterns of the Ta_0.7Nb_0.3Sb₂ single crystal. (h) HRTEM image. (i) SAED pattern.

Fig.2 (a) Zero-field resistivity (cyan points) and fitting results (red curve) of the Ta_0.7Nb_0.3Sb₂ single crystal. Inset: schematic geometry of the directions of the magnetic field and the electric current. (b) Temperature dependence of the resistivity under different magnetic fields, as measured using the schematic geometry shown in the inset of (a). The grey shadow areas show the resistance plateau region and the pink dash arrow indicates the resistance minimum temperature (T_m). (c) ∂ρ_xx/∂T plotted as a function of temperature, taking B = 3 T as an example. Insert: T_m plotted as a function of the magnetic field B.

Fig.3 (a) Hall resistivity as a function of the magnetic field at different fixed temperatures for the Ta_0.7Nb_0.3Sb₂ single crystal. (b) Double-band model fitting of the Hall resistivity versus magnetic field curves. (c) Temperature dependence of the carrier’s density and mobility, obtained via the double-band fitting.

Fig.4 (a) MR plotted as a function of the magnetic field B at different fixed temperatures for the Ta_0.7Nb_0.3Sb₂ single crystal. (b) A zoom-in MR measurements below 50 K ranging from −3 T to 3 T. (c) MR plotted as a function of the magnetic field at various angles θ at T = 2 K. Insets: Schematic diagrams of the directions of the magnetic field, electric current and crystallographic orientation during different types of MR measurements.

Fig.5 (a) Magnetoconductance

Δ G ~

as a function of the magnetic field. The solid lines are the fitting results using HLN model. (b) Temperature dependence of the parameter α and the phase coherence length l_ϕ, extracted from the HLN model. The solid blue line is the fitting curve using equation (5). (c) Angular dependence of the magnetoconductance as a function Bsinθ, as measured at T = 2 K.

Fig.6 Angular dependent MR at T = 2 K and various magnetic fields for the Ta_0.7Nb_0.3Sb₂ single crystal.

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