Nd_(2-x)Sr_xCoO_4(x=1.25,1.33,1.60)体系的物理性质研究  

THE DETAILED PHYSICAL PROPERTIES OF Nd_(2-x)Sr_xCoO_4(x=1.25,1.33,1.60)

作　　者：黄胜利[1] 阮可青[1] 吕章明[1] 魏鹏[1] 曹烈兆[1] 孙玉平[2] 

机构地区：[1]中国科学技术大学结构分析开放实验室,物理系合肥230026 [2]中国科学院固体物理研究所

出　　处：《低温物理学报》2005年第A01期509-514,共6页Low Temperature Physical Letters

基　　金：国家自然科学基金(项目编号:10104013);国家重点基础研究专项经费(项目编号:G19990646)资助的课题~~

摘　　要：用固相反应法制备了Nd2-xSrxCoO4(x=1.25,1.33,1.60)多晶.X射线衍射结果表明样品没有杂项,且都是四方层状K2NiF4结构[1].电阻率结果表明这组样品在测量温区都是半导体行为.对于x=1.25和1.33的样品,热电势为正值;而对于x=1.60的样品,热电势在60K发生了由正到负的转变.所有样品在80K左右零场冷却磁化率有个缓变的最大值,在180K左右场冷和零场冷磁化率发生劈裂,表明在低温下样品存在类自旋玻璃态.我们同时测量了x=1.25样品在110K到300K温区的电子自旋共振谱,发现在居里温度左右存在顺磁相和铁磁相激烈竞争,强烈的轨道-自旋耦合导致了短自旋-晶格驰豫时间使谱线宽化.Polycrystalline samples of Nd2-xSrxCoO4（x=1.25,1.33,1.60） were prepared by a conventional solid-stated reaction. The results of X-ray diffraction confirmed that the samples were pure and had a tetragonal K2 NiF4-type structure. The relationship between reaistivity and temperature showed that all the samples were semiconductors. For the samples with x=1.25 and x= 1.33, the thermopower was positive. But for the sample with x=1. 66, the thermopower changed from positive to negative at 60K. Magnetic measurements indicated the samples were in the spin-glass states at low temperature. Through electron spin resonance measurement we found that ferromagnetic and paramagnetic regions competed with each other severely around Curie temperature in the sample with x=1.25. The intense coupling between orbit and spin caused a short relational time of spin and lattice, thus widened the spectrum.

关 键 词：输运性质 自旋玻璃态 居里温度 

分 类 号：O511.4[理学—低温物理]