R. Yevych, V. Liubachko, V. Hryts, M. Medulych, A. Kohutych, Y. Vysochanskii
{"title":"Description of CuInP2S6 ferrielectrics in a mixed Ising model","authors":"R. Yevych, V. Liubachko, V. Hryts, M. Medulych, A. Kohutych, Y. Vysochanskii","doi":"10.5488/CMP.27.14701","DOIUrl":null,"url":null,"abstract":"The appearance of spontaneous polarization in CuInP2S6 ferrielectrics is related to the second order Jahn-Teller effect for copper cations located in a double-well local potential, the stereoactivity of indium cations located in a three-well local potential, as well as the valence fluctuations of phosphorus cations. The paraelectric to ferrielectric phase transition is primarily determined by the coupling of indium cations with their surroundings. This transition can be analyzed using the mixed Ising model with spins s = 1/2 and S = 1. The spectrum of pseudospin fluctuations at different temperatures was calculated using a mean-field approach for a set of quantum anharmonic oscillators. The results were then compared with Raman spectroscopy data for CuInP2S6 crystal. The analysis indicates that the lattice anharmonicity below 150 K, is mainly determined by the indium sublattice, leading to the coexistence of the glassy state and ferrielectric phase. Above 150 K, the anharmonicity of the copper sublattice activates the ionic conductivity and results in the existence of a long-ranged fluctuated cluster of spontaneous polarization in a temperature interval of the paraelectric phase above TC.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.9000,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Condensed Matter Physics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.5488/CMP.27.14701","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PHYSICS, CONDENSED MATTER","Score":null,"Total":0}
引用次数: 0
Abstract
The appearance of spontaneous polarization in CuInP2S6 ferrielectrics is related to the second order Jahn-Teller effect for copper cations located in a double-well local potential, the stereoactivity of indium cations located in a three-well local potential, as well as the valence fluctuations of phosphorus cations. The paraelectric to ferrielectric phase transition is primarily determined by the coupling of indium cations with their surroundings. This transition can be analyzed using the mixed Ising model with spins s = 1/2 and S = 1. The spectrum of pseudospin fluctuations at different temperatures was calculated using a mean-field approach for a set of quantum anharmonic oscillators. The results were then compared with Raman spectroscopy data for CuInP2S6 crystal. The analysis indicates that the lattice anharmonicity below 150 K, is mainly determined by the indium sublattice, leading to the coexistence of the glassy state and ferrielectric phase. Above 150 K, the anharmonicity of the copper sublattice activates the ionic conductivity and results in the existence of a long-ranged fluctuated cluster of spontaneous polarization in a temperature interval of the paraelectric phase above TC.
CuInP2S6 铁电体中自发极化的出现与位于双阱局部电势中的铜阳离子的二阶贾恩-泰勒效应、位于三阱局部电势中的铟阳离子的立体活性以及磷阳离子的价态波动有关。介电相到铁电相的转变主要是由铟阳离子与其周围环境的耦合决定的。这种转变可以使用自旋 s = 1/2 和 S = 1 的混合伊辛模型进行分析。利用一组量子非谐振子的均场方法计算了不同温度下的伪自旋波动谱。然后将计算结果与 CuInP2S6 晶体的拉曼光谱数据进行了比较。分析表明,150 K 以下的晶格非谐波性主要由铟亚晶格决定,导致玻璃态和铁电相共存。在 150 K 以上,铜亚晶格的非谐波性激活了离子导电性,导致在 TC 以上的副电相温度区间内存在一个长范围波动的自发极化簇。
期刊介绍:
Condensed Matter Physics contains original and review articles in the field of statistical mechanics and thermodynamics of equilibrium and nonequilibrium processes, relativistic mechanics of interacting particle systems.The main attention is paid to physics of solid, liquid and amorphous systems, phase equilibria and phase transitions, thermal, structural, electric, magnetic and optical properties of condensed matter. Condensed Matter Physics is published quarterly.