Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                

Effects of filling, strain, and electric field on the Néel vector in antiferromagnetic CrSb

In Jun Park, Sohee Kwon, and Roger K. Lake
Phys. Rev. B 102, 224426 – Published 23 December 2020
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • INTRODUCTION
  • METHODS
  • RESULTS AND DISCUSSION
  • SUMMARY AND CONCLUSIONS
  • ACKNOWLEDGMENTS
    • References

    Abstract

    CrSb is a layered antiferromagnet (AFM) with perpendicular magnetic anisotropy, a high Néel temperature, and large spin-orbit coupling (SOC), which makes it interesting for AFM spintronic applications. To elucidate the various mechanisms of Néel vector control, the effects of strain, band filling, and electric field on the magnetic anisotropy energy (MAE) of bulk and thin-film CrSb are determined and analyzed using density functional theory. The MAE of the bulk crystal is large (1.2 meV per unit cell). Due to the significant ionic nature of the Cr-Sb bond, finite slabs are strongly affected by end termination. Truncation of the bulk crystal to a thin film with one surface terminated with Cr and the other surface terminated with Sb breaks inversion symmetry, creates a large charge dipole and average electric field across the film, and breaks spin degeneracy, such that the thin film becomes a ferrimagnet. The MAE is reduced such that its sign can be switched with realistic strain, and the large SOC gives rise to an intrinsic voltage controlled magnetic anisotropy. A slab terminated on both faces with Cr remains a compensated AFM, but with the compensation occurring nonlocally between mirror-symmetric Cr pairs. In-plane alignment of the moments is preferred, the magnitude of the MAE remains large, similar to that of the bulk, and it is relatively insensitive to filling.

    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    1 More
    • Received 11 June 2020
    • Revised 6 December 2020
    • Accepted 8 December 2020

    DOI:https://doi.org/10.1103/PhysRevB.102.224426

    ©2020 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Electronic structureMagnetic anisotropyMagnetization switchingMagnetoelectric effectSpintronicsSurface & interfacial phenomena
    1. Physical Systems
    Antiferromagnets
    1. Techniques
    First-principles calculations
    Condensed Matter, Materials & Applied Physics

    Authors & Affiliations

    In Jun Park*, Sohee Kwon, and Roger K. Lake†

    • Laboratory for Terahertz &Terascale Electronics (LATTE), Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA

    • *ipark008@ucr.edu
    • †Corresponding author: rlake@ece.ucr.edu

    Article Text (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 102, Iss. 22 — 1 December 2020

    Reuse & Permissions
    Access Options
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      (a) Bulk antiferromagnetic CrSb crystal structure and spin texture in the ground state. Blue and brown spheres indicate the Cr and Sb atoms, respectively. (b) 1.1-nm thin film with a thickness of 2 u.c. (c) The same thin film as in (b) but with the top Sb layer removed. The numbers index the Cr atoms, and the arrow indicates the direction of positive applied external electric field for VCMA calculations.

      Reuse & Permissions
    • Figure 2
      Figure 2

      The d-orbital-resolved band structures (without SOC) of bulk CrSb when the electron number is (a) 22 (equilibrium) and (b) 21. For both (a) and (b), the top panel is for spin up, and the bottom panel is for spin down. The colors indicate the different d orbitals, as indicated by the legends. The line thicknesses indicate the relative weights. (c) The band structure of CrSb in equilibrium with SOC.

      Reuse & Permissions
    • Figure 3
      Figure 3

      MAE as a function of applied strain for (a) the bulk crystal and for the asymmetric (b) 1.1-nm and (c) 1.6-nm thin films.

      Reuse & Permissions
    • Figure 4
      Figure 4

      MAE of bulk crystal vs the number of electrons in the unit cell.

      Reuse & Permissions
    • Figure 5
      Figure 5

      The net electronic charges on the Cr and Sb atoms, calculated from the Bader charges, in units of |e|, of (a) bulk and (c) 1.1-nm thin-film CrSb in equilibrium. (b) Change in net electronic bulk charge due to hole doping of 0.5 holes/u.c. (d) The planar-averaged Hartree potential of the 1.1-nm thin film CrSb in equilibrium. (e) Change in the net electronic charges induced by the electric field (indicated in the legend) with the reference charge taken from equilibrium charges shown in (c). Note that a net positive electronic charge corresponds to a depletion of the electron density.

      Reuse & Permissions
    • Figure 6
      Figure 6

      (a) Spin-resolved band structure of the 1.1-nm CrSb thin film in equilibrium. (b), (c) The d-orbital-resolved band structures of the 1.1-nm CrSb thin film under electric fields of (b) −1 V/nm and (c) 3.2 V/nm. The line colors indicate the d-orbital composition as given by the legends, and the line thicknesses indicate the relative weights.

      Reuse & Permissions
    • Figure 7
      Figure 7

      MAEs of (a) 1.1-nm and (b) 1.6-nm films as a function of applied electric field.

      Reuse & Permissions
    • Figure 8
      Figure 8

      The change in the planar-averaged electronic charge (red) and planar-averaged Hartree energy (black) of 1.1-nm thin-film CrSb with an electric field of (a) −1 V/nm and (b) 3.2 V/nm. The arrow indicates the direction of applied electric field. Note that a positive electronic charge corresponds to a depletion of the electron density.

      Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review B

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×