Observation of Spin‐Induced Ferroelectricity in a Layered van der Waals Antiferromagnet CuCrP2S6

Abstract CuCrP 2 S 6 , a van der Waals magnet having stacked layers of 2D honeycomb lattice made of CuS 3 triangles and CrS 6 octahedra, exhibits an A‐type antiferromagnetic order with the Néel temperature ( T N ) = 32 K. Upon in‐plane magnetic field ( H ) being applied below T N , H ‐induced modulation of the c *‐axis electric polarization (Δ P c* ) is found at fields lower than the saturation field µ 0 H S = 6.1 T, at which a forced ferromagnetic alignment sets in. Based on the symmetry analyses and dependence of Δ P c* on H and the azimuthal angle of applied H direction, a microscopic origin of the magnetoelectric (ME) coupling is attributed to the spin‐direction‐dependent p – d hybridization that is allowed due to the presence of off‐centered Cr 3+ octahedra. A comparative study on CuCrP 2 Se 6 , however, finds no H ‐induced P modulation due to cancellation of P between neighboring layers with the doubling of a crystallographic unit cell at T N . As the p – d hybridization mechanism allows generation of P in a single Cr atom–ligand pair, the results imply that large ME coupling should exist even in a single layer limit of CuCrP 2 S 6 .