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Spontaneous Anomalous Hall Effect Arising from an Unconventional Compensated Magnetic Phase in a Semiconductor

R. D. Gonzalez Betancourt, J. Zubáč, R. Gonzalez-Hernandez, K. Geishendorf, Z. Šobáň, G. Springholz, K. Olejník, L. Šmejkal, J. Sinova, T. Jungwirth, S. T. B. Goennenwein, A. Thomas, H. Reichlová, J. Železný, and D. Kriegner
Phys. Rev. Lett. 130, 036702 – Published 20 January 2023
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    Abstract

    The anomalous Hall effect, commonly observed in metallic magnets, has been established to originate from the time-reversal symmetry breaking by an internal macroscopic magnetization in ferromagnets or by a noncollinear magnetic order. Here we observe a spontaneous anomalous Hall signal in the absence of an external magnetic field in an epitaxial film of MnTe, which is a semiconductor with a collinear antiparallel magnetic ordering of Mn moments and a vanishing net magnetization. The anomalous Hall effect arises from an unconventional phase with strong time-reversal symmetry breaking and alternating spin polarization in real-space crystal structure and momentum-space electronic structure. The anisotropic crystal environment of magnetic Mn atoms due to the nonmagnetic Te atoms is essential for establishing the unconventional phase and generating the anomalous Hall effect.

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    • Received 31 May 2022
    • Revised 10 October 2022
    • Accepted 21 December 2022

    DOI:https://doi.org/10.1103/PhysRevLett.130.036702

    © 2023 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Anomalous Hall effectElectronic structureFirst-principles calculationsHall effectMagnetismMagnetotransportSpintronics
    Condensed Matter, Materials & Applied Physics

    Authors & Affiliations

    R. D. Gonzalez Betancourt1,2,3, J. Zubáč2,4, R. Gonzalez-Hernandez5,*, K. Geishendorf2, Z. Šobáň2, G. Springholz6, K. Olejník2, L. Šmejkal7,2, J. Sinova7,2, T. Jungwirth2,8, S. T. B. Goennenwein9,1, A. Thomas1,3, H. Reichlová1, J. Železný2, and D. Kriegner1,2,†

    • 1Institute of Solid State and Materials Physics, Technical University Dresden, 01062 Dresden, Germany
    • 2Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
    • 3Leibniz Institute of Solid State and Materials Research (IFW Dresden), Helmholtzstr. 20, 01069 Dresden, Germany
    • 4Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
    • 5Departamento de Fisica y Geociencias, Universidad del Norte, Barranquilla 080020, Colombia
    • 6Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
    • 7Institut für Physik, Johannes Gutenberg Universität Mainz, 55128 Mainz, Germany
    • 8School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
    • 9Department of Physics, University of Konstanz, 78457 Konstanz, Germany

    • *rhernandezj@uninorte.edu.co
    • †kriegner@fzu.cz

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    Issue

    Vol. 130, Iss. 3 — 20 January 2023

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    Images

    • Figure 1
      Figure 1

      Theoretical calculation of spontaneous anomalous Hall signal in collinear MnTe: (a) Atomic configuration of Mn (blue or red) and Te (gold) with hexagonal NiAs structure. The two magnetic sublattices are connected by a sixfold screw axis along [0001]. (b) and (c) Magnetic moment configurations of the hexagonal c planes with magnetic moments (red arrows) oriented along [11¯00] and [21¯1¯0], respectively. The magnetic unit cell shape (black line) and crystal symmetry operations corresponding to the generators of the magnetic point groups are indicated in the panels. Te atoms at different heights are indicated by different color saturation. (d) DFT Anomalous Hall conductivity vs. Fermi energy calculated for the moment configuration of panel (b) and Hall current along x direction. (e) Transverse conductivity components for the Fermi energy 0.25 eV below the valence band maximum as a function of the Néel vector orientation. The angle ϕ is defined with respect to the a axis.

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    • Figure 2
      Figure 2

      Magnetic field sweep measurements and AHE at T=150  K. (a) Microscopy image of the Hall bar together with electrical schematics of our measurement. For all transport measurements a moderate current density j∼8×106  A/m2 was used. (b) and (c) Transverse and longitudinal resistivities measured during magnetic field sweeps in a geometry indicated by the sketch in (b). (d) Inferred anomalous Hall resistivity given by ρyxAHE≡ρyx−ρyxOHE−ρyxeven (see text).

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    • Figure 3
      Figure 3

      (a) SQUID magnetization obtained for in-plane and out-of-plane magnetic field measured at 10 K on a 2000 nm thick film. To highlight the absence of remanent magnetization a linear slope obtained in vicinity of zero magnetic field was subtracted from each dataset. Note that the slope contains the susceptibility of MnTe as well as the diamagnetic substrate. (b) AHE conductivity σxyAHE obtained from the measured ρyxAHE at 175 and 300 K, and β=30°. (c) and (d) Temperature dependence of the spontaneous zero-field and saturated AHE conductivity.

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