The layered van der Waals(vdW)ferroelectric CuInP2S6(CIPS)exhibits unique cation-hopping-driven phenomena that bring about unconventional properties with intriguing mechanisms and hold promise for advanced application...The layered van der Waals(vdW)ferroelectric CuInP2S6(CIPS)exhibits unique cation-hopping-driven phenomena that bring about unconventional properties with intriguing mechanisms and hold promise for advanced applications in nanoelectronics.However,an explicit analysis of its lattice dynamics and vibrational symmetries,pivotal for understanding the material’s peculiar ferroelectric and ferroionic behaviors,remains incomplete.Here,we employ angle-resolved polarized Raman spectroscopy in concert with first-principles calculations to systematically unravel the anisotropic lattice vibrations of CIPS single crystals.By analyzing the polarization-dependent Raman intensities,we determine the symmetry assignments and Raman tensors of all major vibrational modes,revealing good agreement with theoretical predictions.Furthermore,we demonstrate the utility of Raman spectroscopy as a sensitive and non-invasive probe for structural and ferroelectric order evolution by examining temperature-driven phase transitions and thickness-dependent polarization suppression in CIPS.Our findings establish a foundational framework for correlating lattice dynamics with functional properties in CIPS and provide a methodological blueprint for studying other vdW ferroelectrics.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12474089,12574102 for L.Y.and L.F.,and 12404102 for J.Z.)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions(for L.Y.and L.F.)+2 种基金the Natural Science Foundation of the Jiangsu Province(Grant No.BK20230806 for J.Z.)Southeast University Interdisciplinary Research Program for Young Scholars(Grant No.2024FGC1008 for J.Z.)the support by the State Key Laboratory of Solid State Microstructures(Nanjing University)(No.M37067)。
文摘The layered van der Waals(vdW)ferroelectric CuInP2S6(CIPS)exhibits unique cation-hopping-driven phenomena that bring about unconventional properties with intriguing mechanisms and hold promise for advanced applications in nanoelectronics.However,an explicit analysis of its lattice dynamics and vibrational symmetries,pivotal for understanding the material’s peculiar ferroelectric and ferroionic behaviors,remains incomplete.Here,we employ angle-resolved polarized Raman spectroscopy in concert with first-principles calculations to systematically unravel the anisotropic lattice vibrations of CIPS single crystals.By analyzing the polarization-dependent Raman intensities,we determine the symmetry assignments and Raman tensors of all major vibrational modes,revealing good agreement with theoretical predictions.Furthermore,we demonstrate the utility of Raman spectroscopy as a sensitive and non-invasive probe for structural and ferroelectric order evolution by examining temperature-driven phase transitions and thickness-dependent polarization suppression in CIPS.Our findings establish a foundational framework for correlating lattice dynamics with functional properties in CIPS and provide a methodological blueprint for studying other vdW ferroelectrics.
