Magnetic Structure and Metamagnetic Transitions in the van der Waals Antiferromagnet CrPS₄

Abstract

In 2D magnets, interlayer exchange coupling is generally weak due to the van der Waals layered structure but it still plays a vital role in stabilizing the long‐range magnetic ordering and determining the magnetic properties. Using complementary neutron diffraction, magnetic, and torque measurements, the complete magnetic phase diagram of CrPS4 crystals is determined. CrPS4 shows an antiferromagnetic ground state (A‐type) formed by out‐of‐plane ferromagnetic monolayers with interlayer antiferromagnetic coupling along the c axis below TN = 38 K. Due to small magnetic anisotropy energy and weak interlayer coupling, the low‐field metamagnetic transitions in CrPS4, that is, a spin‐flop transition at ≈0.7 T and a spin‐flip transition from antiferromagnetic to ferromagnetic under a relatively low field of 8 T, can be realized for H∥c. Intriguingly, with an inherent in‐plane lattice anisotropy, spin‐flop‐induced moment realignment in CrPS4 for H∥c is parallel to the quasi‐1D chains of CrS6 octahedra. The peculiar metamagnetic transitions and in‐plane anisotropy make few‐layer CrPS4 flakes a fascinating platform for studying 2D magnetism and for exploring prototype device applications in spintronics and optoelectronics.

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

“…Having found the occurrence of band gap crossover in CrPS 4 , we then investigated the possible magnetic transformation under pressure as derived from the DFT + U (U = 2 eV) calculations. At ambient pressure, we found that the A-type AFM structure is the most energetically favorable state, consistent with previous DFT studies 40 and recent neutron diffraction experiments 35 . Our calculations suggest that the A-type AFM structure remains stable and no signs of change in the magnetic state is predicted to occur under pressure up to 20 GPa (see Supplementary Fig.…”

“…Among the 2D vdW magnetic materials, CrPS 4 is currently enjoying a surge of interest [30][31][32][33][34][35] . CrPS 4 was first synthesized in the 1970s and found to possess a monoclinic symmetry (C2/m space group) 36 .…”

“…Previous magnetic studies suggested a C-type antiferromagnetic structure (antiferromagnetic interaction within a layer and ferromagnetic interaction between the layer) below the Néel temperature (T N ) of 36 K 38 . However, recent neutron diffraction and torque magnetometry investigations revealed an A-type AFM structure with the intralayer ferromagnetic interaction and interlayer antiferromagnetic coupling along the c axis 35 . X-ray spectroscopy studies demonstrated that the Cr 3d bands are localized within the energy gap in the vicinity of the Fermi level, where the lower and higher energy of the band structure is dominated by the non-bonding S 3p band and the S 3s band, respectively 39 .…”

Variation between Antiferromagnetism and Ferrimagnetism in NiPS3 by Electron Doping

“…Since the first experimental observation of intrinsic ferromagnetism in monolayer CrI 3 1 and bilayer Cr 2 Ge 2 Te 6 2 , van der Waals (vdW) magnetic materials have attracted extensive attention in both fundamental research and practical applications [3][4][5][6][7][8][9] . The field of two-dimensional (2D) magnetic materials grows rapidly and various types of 2D magnetic materials have been discovered and synthesized, such as ferromagnetic (FM) magnets including Cr 2 Ge 2 Te 6 2 , CrBr 3 10 , Fe 3 GeTe 2 11,12 , Fe 5 GeTe 2 13 , monolayer VSe 2 14 , etc., and antiferromagnetic (AFM) magnets including CrCl 3 15 , transition metal phosphorous trichalcogenides MPX 3 (M = Mn, Fe, Ni; X = S, Se) [16][17][18][19] , CrPS 4 20 , MnBi 2 Te 4 21 , etc. The distinct spin-dependent properties of these materials provide a promising platform for the discovery and study of new quantum phenomena and design of novel spintronic devices.…”

Controlling Spin Orientation and Metamagnetic Transitions in Anisotropic van der Waals Antiferromagnet CrPS4 by Hydrostatic Pressure

“…[34] In our previous study, the low-field metamagnetic transition of CrPS 4 was identified as a spin-flop transition. [31] During the spin-flop transition, magnetic moments realign from the ac plane (at a small angle from the c axis) to the quasi-1D chains of CrS 6 octahedra along the b axis, showing both in-plane and out-of-plane magnetic anisotropy in CrPS 4 . Strong in-plane optical anisotropy has also been observed in CrPS 4 flakes, [33] confirming the inherent anisotropy of CrPS 4 .…”