Abstract
CuCrP2S6 (CCPS), a type-II multiferroic material, exhibits unique phase transitions involving ferroelectric, antiferroelectric, and antiferromagnetic ordering. In this study, we conduct a comprehensive investigation on the intricate phase transitions and their multiferroic couplings in CCPS across a wide temperature range from 4 to 345 K through Raman spectroscopic measurements down to 5 cm-1. We first assign the observed Raman modes with the support of theoretical calculations and angle-resolved polarized Raman measurements. We further present clear signatures of phase transitions from the analyses of temperature-dependent Raman spectral parameters. Particularly, two low-frequency soft modes are observed at 36.1 cm-1 and 70.5 cm-1 below 145 K, indicating the antiferroelectric to quasi-antiferroelectric transition. Moreover, phonon mode hardening is observed when the temperature increases from 4 to 65 K, suggesting negative thermal expansion (NTE) and strong magnetoelastic coupling below 65 K. These findings advance the understanding of vdW multiferroic CCPS, paving the way for future design and engineering of multiferroicity in cutting-edge technologies, such as spintronics and quantum devices.
| Original language | English |
|---|---|
| Pages (from-to) | 4336-4345 |
| Number of pages | 10 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 16 |
| Issue number | 17 |
| DOIs | |
| State | Published - May 1 2025 |
Funding
This material is based upon work supported by the National Science Foundation (NSF) under Grant 1945364. Work done by X.L. was also supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Science (BES) under Award DE-SC0021064 and NSF under Grant No. 2216008. The Raman spectroscopies and magnetic properties measurements were supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy Office of Science User Facility at Oak Ridge National Laboratory with additional support for cryogenic Raman spectroscopies provided by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The XRD measurement was supported by NSF under the Award No. 1337471 and the BU MSE Core Research Facility. The computational work done at MIT is supported by DOE BES Award DE-SC0021940 and NSF Award DMR-2118448. J.T. and X.L. also thank Riichiro Saito and Nguyen Tuan Hung at the Tohoku University in Japan for the discussion on DFT calculations on the Raman spectra of CCPS and Anna Swan from Boston University for her valuable discussions on the Raman spectra analysis.