Tunable magnetism in layered CoPS3 by pressure and carrier doping

Abstract

Despite extensive research on recently discovered layered ferromagnetic (FM) materials, their further development is hampered by the limited number of candidate materials with desired properties. As a much bigger family, layered antiferromagnetic (AFM) materials represent excellent platforms to not only deepen our understanding of fundamental physics but also push forward high-performance spintronics applications. Here, by systematic first-principles calculations, we demonstrate pressure and carrier doping control of magnetic properties in layered AFM CoPS 3 , a representative of transition metal phosphorus trichalcogenides. In particular, pressure can drive isostructural Mott transition, in sharp contrast to other transition metal thiophosphates. Intriguingly, both pressure and carrier doping can realize the long-sought FM half-metallic states with 100% spin polarization percentage, which is good for improving the injection and detection efficiency of spin currents among others. Moreover, the Mott transition is accompanied by instantaneous spincrossover (SCO) in CoPS 3 , and such cooperative SCO facilitates the implementation of fast-response reversible devices, such as data storage devices, optical displays and sensors. We further provide an in-depth analysis for the mechanisms of FM half-metallicity and SCO. Tunable magnetism in layered AFM materials opens vast opportunities for purposeful device design with various functionalities.

Pressure-Enhanced Ferromagnetism in Layered CrSiTe3 Flakes

“…The extracted coercive field from samples 1 and 2 in Figure b shows a dramatic increase as pressure increases from a threshold pressure of around 4 GPa to around 7.8 GPa. Above 7.8 GPa, we cannot detect any MCD signal due to a structural transition at ∼7.5 GPa accompanied by a ferromagnetic-paramagnetic phase transition (data are not shown). A pressure-induced insulator–metal transition in CrSiTe 3 and CrGeTe 3 has been reported previously. , Although we did not directly observe such an insulator–metal transition, we notice that the pressure-dependent Raman measurements (Figure S4) also reveal negligible peaks above 7.8 GPa at room temperature, consistent with a metallic state in CrSiTe 3 .…”

“…As pressure increases further, the area of hysteresis loop increases and the corresponding coercive field also increases from 0.02 T at 4.6 GPa to 0.17 T at 7.8 GPa. Above 7.8 GPa, we cannot detect any MCD signal due to a structural transition at ~ 7.5 GPa accompanied by a ferromagnetic-paramagnetic phase transition 11 (data are not shown). As summarized in Figure 2b, the coercive field dramatically increases as pressure increases, with a threshold pressure around 4 GPa.…”

“…Compared with bulk cases, the magnetic states of 2D ferromagnets show greater controllability by external stimuli, 3,[6][7][8][9][10][11] which may improve their magneto-crystalline anisotropy and exchange interaction, thereby expanding their applications and deepening our understanding of the underlying mechanism of magnetism in 2D systems. Hydrostatic pressure is one of the practical and easy-to-implement routes for controlling 2D magnetic states [12][13][14][15][16] .…”

“…Compared to those in bulk counterparts, the magnetic states of 2D ferromagnets show greater controllability by external stimuli, ,− which may improve their exchange interactions, thereby deepening our understanding of the underlying mechanisms of magnetism in 2D systems. In this regard, hydrostatic pressure is one of the direct routes for dynamically modifying both the crystal and band structures of materials. − It can effectively tune the distance between adjacent atomic layers, as well as bond lengths and bond angles of intralayer atoms in 2D magnets, leading to modulation of interlayer and intralayer exchange interactions.…”

Moiré bands in twisted trilayer black phosphorene: effects of pressure and electric field

“…Previous work has shown that external pressure acts as an effective approach to tune the structural, 45 electronic, 35 magnetic, 52–54 and topological 46 properties of layered materials, in particular for bP. 35,45,46 Here, the external pressure is simulated by decreasing the thickness of trilayer bP (defined by the vertical distance between the top and bottom P atoms) to investigate the evolution of the electronic structure.…”