Shubnikov--de Haas oscillations and electronic structure in the Dirac semimetal SrAgAs

Shubnikov–de Haas oscillations and electronic structure in the Dirac semimetal SrAgAs

Qinqing Zhu, Qi Wang, Liang Li, Zhihua Yang, Jinhu Yang, Bin Chen, Chao Cao, Hangdong Wang, and Jianhua Du

Phys. Rev. B 104, 144305 – Published 25 October 2021

Abstract

The physical properties and electronic structure of the layered SrAgAs single crystal have been systematically studied via transport measurements and first-principles calculations. The Landau level index derived from the low-temperature Shubnikov–de Haas oscillations suggests nontrivial Berry phase of the Fermi surface. In addition, the compound exhibits high transport mobility in the whole measured temperature range. First-principles calculations indicate that the stoichiometry compound is an ideal Dirac semimetal close to semimetal-topological-insulator transition. Due to its perfect Dirac semimetallic nature, the shape and size of the Fermi surfaces could be drastically tuned by charge doping.

Received 6 May 2021
Revised 5 October 2021
Accepted 6 October 2021

DOI:https://doi.org/10.1103/PhysRevB.104.144305

Physics Subject Headings (PhySH)

Electronic structure Shubnikov-de Haas effect Topological phases of matter Transport phenomena

Dirac semimetal

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Qinqing Zhu^*, Qi Wang^*, Liang Li, Zhihua Yang, Jinhu Yang, Bin Chen, Chao Cao^†, and Hangdong Wang ^‡

Hangzhou Key Laboratory of Quantum Matter, School of Physics, Hangzhou Normal University, Hangzhou 311121, China

Jianhua Du

Department of Physics, China Jiliang University, Hangzhou 310018, China

^*These authors contributed equally to this work.
^†ccao@hznu.edu.cn
^‡hdwang@hznu.edu.cn

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Vol. 104, Iss. 14 — 1 October 2021

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Images

Figure 1
(a) The crystal structure of SrAgAs. (b) EDX spectrum of the SrAgAs single crystal. (c) XRD pattern of the as-grown SrAgAs single crystal. Inset: A photo of the SrAgAs crystal. (d) Powder XRD pattern of SrAgAs. The peaks of the impurity phase have been marked with asterisks.
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Figure 2
(a) Temperature dependence of the in-plane resistivity $ρ_{x x}$ and the out-plane resistivity $ρ_{z}$ , respectively. (b) Field dependence of the MR collected at several temperatures up to 9 T. Oscillatory component (c) and the FFT spectra (d) of $Δ ρ_{x x}$ at various temperatures (2, 3, 4, 5, 7, 10, 11.5, 13, 16, and 20 K). The inset of (d) indicates the temperature dependence of the FFT amplitude. The solid black curve represents the fit of the LK formula.
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Figure 3
(a) Field dependence of the hall resistivity for SrAgAs at several selected temperatures. (b) Temperature dependence of the Hall coefficient $R_{H}$ (left) and transport mobility $μ_{t r}$ (right). (c) The in-plane oscillatory conductivity $Δ σ_{x x}$ vs. $1 / B$ at 2 K. The inset is the in-plane conductivity $σ_{x x}$ converted from the $ρ_{x x}$ and $ρ_{y x}$ data. (d) The Landau Level (LL) index fan diagram derived from the oscillatory conductivity $Δ σ_{x x}$ at 2 K. The solid circles and the hollow circles represent the integer index (valley) and the half integer index (peak), respectively.
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Figure 4
(a) The polar plot of MR at $T$ = 2 K measured under $B$ = 3, 6, and 9 T fields. (b) Field dependence of the MR with different tilt angles $θ$ at 2 K. Inset: Schematic diagram of the measurement setup; field angle $θ$ is defined as the angle between the magnetic field $B$ and the $c$ axis. (c) The oscillatory component, $Δ ρ_{x x}$ , as a function of $1 / B$ , measured at $θ$ = 0, 10, 20, 25, and 30 degrees. The data have been shifted for clarity. (d) The FFT spectra of $Δ ρ_{x x} (B)$ at different $θ$ . The inset is the SdH oscillation frequency as a function of $θ$ .
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Figure 5
First-principles result of SrAgAs using PBE. (a) Band structure with (solid lines) and without (dashed lines) SOC (left panel) and the electronic DOS (right panel). The weight of As-4p, As-5s, and Sr-4d orbitals are indicated by the radius of red, blue, and green circles in the left panel. (b) Fermi surface of pristine crystal (upper panel) and after $E_{F}$ shifted down 0.036 eV (bottom panel). (c) The calculated azimuthal angular dependence of SdH frequencies for the Fermi surface obtained with shifted $E_{F}$ . (d) The band structure between $Γ$ and A for compressed $c$ .
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Figure 6
Band structure of SrAgAs using the mBJ method.
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