Current Control of Magnetism in Two-Dimensional Fe3GeTe2

Abstract

The recent discovery of magnetism in two-dimensional van der Waals systems opens the door to discovering exciting physics. We investigate how a current can control the ferromagnetic properties of such materials. Using symmetry arguments, we identify a recently realized system in which the current-induced spin torque is particularly simple and powerful. In Fe 3 GeTe 2 , a single parameter determines the strength of the spin-orbit torque for a uniform magnetization. The spin-orbit torque acts as an effective out-of-equilibrium free energy. The contribution of the spin-orbit torque to the effective free energy introduces new in-plane magnetic anisotropies to the system. Therefore, we can tune the system from an easy-axis ferromagnet via an easy-plane ferromagnet to another easy-axis ferromagnet with increasing current density. This finding enables unprecedented control and provides the possibility to study the Berezinskiǐ-Kosterlitz-Thouless phase transition in the 2D XY model and its associated critical exponents.arXiv:1812.06096v2 [cond-mat.mes-hall]

Gigantic Current Control of Coercive Field and Magnetic Memory Based on Nanometer‐Thin Ferromagnetic van der Waals Fe3GeTe2

“…Figure a shows the crystal structure of a monolayer Fe 3 GeTe 2 with the distinct three symmetries: the three‐fold rotation symmetry around the c‐axis ( z ‐axis), the mirror reflection symmetry with respect to the a‐axis ( y ‐axis), and the mirror reflection symmetry with respect to the c‐axis. Under this set of symmetries, the general form of H SOT can be expressed as; [ 27 ] where m = ( m x , m y , m z ) = M/|M| and Γ 0 is a coefficient that parametrizes a magnetoelectric coupling strength. Unlike H SOT in other systems, the effective field H SOT of FGT is conservative [ 27 ] and can be obtained from an effective free energy density f SOT by H SOT = −∂ f SOT /∂ M with …”

van der Waals Magnets: Material Family, Detection and Modulation of Magnetism, and Perspective in Spintronics

“…Fe 3 GeTe 2 exhibits high SOT efficiency in the heterostructure with a Pt film, [ 144 ] where the SOT serves as an in‐plane anisotropy. [ 145 ] The magnetization direction of Fe 3 GeTe 2 is switched with increasing the current at a small in‐plane magnetic field of 50 mT (Figure 11g). [ 144,146 ] Besides, SOT is also used to control the magnetization of CrGeTe 3 in a heterostructure with a Ta film.…”

Recent Advances in Two-Dimensional Magnets: Physics and Devices towards Spintronic Applications

“…Torque. Spin-orbit torque (SOT) is a new method for the manipulation of the magnetization in ferromagnetic materials by injecting an in-plane electric current via a large spin-orbit coupling [62]. In a SOT device (see Figure 5(b)), the current flowing through a bilayer system composed of a heavy metal and a ferromagnet can undergo a serious movement in the generated magnetization.…”