Temperature-dependent Raman scattering and x-ray diffraction study of phase transitions in layered multiferroic CuCrP2S6

Crystal Growth, Exfoliation and Magnetic Properties of Quaternary Quasi-Two-Dimensional CuCrP$_2$S$_6$

“…The refined crystal structure model obtained by our Rietveld refinement exhibits zero occupation of the Cu1 site (Wyckoff site 8f) close to the plane shared by all Cr atoms in a layer, in agreement with other structural investigations of this compound [23]. Consequently, all Cu atoms are notably displaced away from the center of their surrounding S 6 octahedra (along c * ).…”

“…Although CuCrP 2 S 6 has recently moved into the focus of materials research due to its interesting ferroelectric properties in combination with a low-dimensional structure, a detailed investigation and understanding of its magnetic properties is missing until now. Colombet et al, who were first to synthesize and investigate this material, already reported the observation of antiferromagnetic order at low temperatures in bulk crystals [17] in agreement with more recent reports [23,24]. However, the coexistence of dominantly ferromagentic interactions and an antiferromagnetic groundstate that has been observed for CuCrP 2 S 6 calls for further investigation in order to fully understand the magnetism and, further on, its implications on the ferroic properties in this 2D material.…”

“…However, below about 270 K ordering of the Cu atoms sets in, which leads to a longrange antipolar order of Cu atoms below 140 K and to an antiferroelectric phase. The complex nature of the antiferroelectric/paraelectric phase transition was recently investigated by Susner et al by temperature dependent Raman scattering and x-ray diffraction experiments [23]. While the different electric phases are linked to the Cu sublattice, the Cr sublattice with Cr 3+ having S = 3/2 gives rise to an antiferromagnetic ground state with an ordering temperature of T N = 30 K [17].…”

“…In CuCrP 2 S 6 , the Cr cations are also located at this position, but the Cu cations are strongly displaced either towards the bottom or top layer of sulfur and a nearly trigonal planar coordination environment. This displacement of the Cu position away from the center of their octahedral S 6 environment gives rise to a local electric dipole moment [17,22,23].…”

Nanoscale Mapping of Cu‐Ion Transport in van der Waals Layered CuCrP2S6

“…The Raman peaks R′, T′, ν 1 and ν 2 correspond to rotations, translations, symmetric stretching and deformation of PS 3 groups in the anion sublattice [P 2 S 6 ] 4− , respectively. [27] As the number of layers decreases, the degradation of Raman intensity occurs, which is attributed to the weakening of the interlayer interaction with the decreasing flake thickness. It is worth noting that a nearly linear relationship between the relative intensity and thickness was observed analogous to that of NiPS 3 , [28,29] which can be used to identify the thickness of a CCPS nanosheet.…”