Pressure-induced modification of the anomalous Hall effect in layered Fe3GeTe2

Abstract

We systematically investigate the influence of high pressure on the electronic transport properties of layered ferromagnetic materials, in particular, those of Fe3GeTe2. Its crystal sustains a hexagonal phase under high pressures up to 25.9 GPa, while the Curie temperature decreases monotonously with the increasing pressure. By applying appropriate pressures, the experimentally measured anomalous Hall conductivity, σ A xy , can be efficiently controlled. Our theoretical study reveals that this finding can be attributed to the shift of the spin-orbit-coupling-induced splitting bands of Fe atoms. With loading compression, σ A xy reaches its maximal value when the Fermi level lies inside the splitting bands and then attenuates when the splitting bands float above the Fermi level. Further compression leads to a prominent suppression of the magnetic moment, which is another physical cause of the decrease in σ A xy at high pressure. These results indicate that the application of pressure is an effective approach in controlling the anomalous Hall conductivity of layered magnetic materials, which elucidates the physical mechanism of the large intrinsic anomalous Hall effect.Introduction-. Anomalous Hall effect has been one of the most attractive but unsolved topics within the condensed matter community ever since its experimental discovery [1]. In general, anomalous Hall effect is closely related to the material magnetization, and its fundamental origin in different materials is debatable: it is commonly rationalized as being extrinsic disorder-induced effects (e.g., skew-scattering and side jump) or intrinsic Berry-phase effect [2][3][4][5][6][7]. Nevertheless, new types of anomalous Hall effects in material systems besides those in ferromagnetic materials (i.e., topological Hall effect in non-collinear antiferromagnetic materials [2-5] and giant anomalous Hall effect in magnetic semimetals [6,7]) continually update our understanding of such a striking but unclear electronic transport phenomenon. Noteworthily, in these materials, the anomalous Hall effect is not simply related to the magnetization that breaks timereversal symmetry; thus, the effect cannot be understood from conventional formation mechanisms. An increasing number of studies have demonstrated that the anomalous Hall effect is intimately connected with the intrinsic Berry-phase effect from spin-orbit couplings. Recent works [1,8] illustrate that anomalous Hall conductivity σ A xy is dominated by σ skew

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

“…The anomalous Hall resistivity of bulk Fe 3 GeTe 2 decreases with increasing the pressure ( Figure a,b), indicating the weakening of magnetism. [ 149 ] It may arise from the pressure‐induced shift of splitting band and the suppression of magnetic moment under pressure. The pressure will also weaken the FM superexchange interaction in bulk CrGeTe 3 , further decreasing its T C .…”

“…Then, it is predicted that the Reproduced with permission. [149] Copyright 2019, American Physical Society. c) The field-dependent magnetoresistance of bulk CrGeTe 3 under different pressures.…”

Band gap crossover and insulator–metal transition in the compressed layered CrPS4

“…Pressure or compressive strain might also be an alternative way to tune the properties of the 2D vdW magnets without introducing disorder or impurities to the system. It has been recently shown that pressure can be effectively used to modify the magnetic, electronic, and optical properties of 2D vdW magnets both in bulk and atomically thin samples [18][19][20][21][22][23][24][25][26][27][28][29] .…”

Molecular Beam Epitaxy and High-Pressure Studies of van der Waals Magnets

“…The electronic properties change as a function of applied pressure, from a metallic state at ambient pressure to a less metallic state with increasing pressure up to 16.2 GPa. In a concurrent report on Fe-rich Fe 3 GeTe 2 (bulk T c = 220 K), researchers denoted a kink in the ρ xx (T) curve which represents the transition from a ferromagnetic phase to a non-magnetic phase after taking a derivative, dρ xx /dT, where this becomes indistinguishable at pressures above 13.4 GPa (T c = 120 K) [288]. In our work, we observe similar broadening of the derivative of the R xx (T) curve in pressures above 4.1 GPa (shown in Figure 8.3c), which makes it challenging to determine the T c from this method.…”