Large magneto-optical effect and magnetic anisotropy energy in two-dimensional metallic ferromagnet Fe3GeTe2
Journal
Physical Review B
Journal Volume
105
Journal Issue
1
Date Issued
2022
Author(s)
Jiang M.-C
Abstract
The recent discovery of long-range magnetic orders in atomically thin semiconductors Cr2Ge2Te6 and CrI3 as well as metal Fe3GeTe2 has opened up exciting opportunities for fundamental physics of two-dimensional (2D) magnetism and also for technological applications based on 2D magnetic materials. To exploit these 2D metallic magnets, the mechanisms that control their physical properties should be well understood. In this paper, based on systematic first-principles density functional theory calculations, we study the magnetic anisotropy energy (MAE) and magneto-optical (MO) effects of ferromagnetic multilayers [mono-, bi-, tri-, tetra-, and pentalayer] and bulk Fe3GeTe2 as well as their connections with the underlying electronic structures of the materials. Firstly, all the considered Fe3GeTe2 structures are found to prefer the out-of-plane magnetization and have gigantic MAEs of ?3.0 meV/f.u. This gigantic perpendicular anisotropy results from the large magnetocrystalline anisotropy energy (MCE), which is ten times larger than the competing magnetic dipolar anisotropy energy. The giant MCEs are attributed to the large Te px,y orbital density of states near the Fermi level and also to the topological nodal point just below the Fermi level at the K points in the Brillouin zone. Secondly, 2D and bulk Fe3GeTe2 also exhibit strong MO effects with their Kerr and Faraday rotation angles being ?1.0? and ?100 deg/μm in the visible-light frequency region, respectively. The strong MO Kerr and Faraday effects are found to result from the large MO conductivity (or strong magnetic circular dichroism) in these ferromagnetic materials. In particular, the calculated MO conductivity spectra are one order of magnitude larger than that of Y3Fe5O12. The calculated MO conductivity spectra are analysed in terms of the dipole-allowed optical transitions at high symmetry Γ, K, and K′ points, which further indicate that atomically thin Fe3GeTe2 films with odd layer-number might exhibit anomalous ferrovalley Hall effect. All these interesting findings thus suggest that 2D and bulk ferromagnetic Fe3GeTe2 are promising materials for high-density MO and spintronic nanodevices. ? 2022 American Physical Society.
Subjects
Calculations; Chromium compounds; Density functional theory; Dichroism; Electronic structure; Fermi level; Ferromagnetic materials; Ferromagnetism; Germanium compounds; Iron compounds; Magnetic anisotropy; Magnetic multilayers; Magnetic semiconductors; Magnetocrystalline anisotropy; Magnets; Tellurium compounds; Fundamental physics; K points; Long range magnetic order; Magnetic anisotropy energy; Magneto-optical; Metallic ferromagnets; Optical conductivity spectra; Technological applications; Thin semiconductor; Two-dimensional; Germanium alloys
Type
journal article