摘要
近年来,新型铬(Cr)基非常规超导体因呈现独特晶体结构和奇异物理性质而备受关注,成为超导领域的研究热点之一.A_(2)Cr_(3)As_(3)(A=K,Rb,Cs)是首个常压下的Cr基超导体系,通过化学方法脱除其中一个A离子,可以获得具有类似准一维结构的ACr_(3)As_(3)超导体.其中,KCr_(3)As_(3)和RbCr_(3)As_(3)的超导转变温度(T_c)可以分别达到~5和~7.3 K其上临界场(μ_(0)H_(c2)(0))远超泡利极限(μ_(0)H_(P)^(BCS)).在前期针对A_(2)Cr_(3)As_(3)的高压研究基础上,本文分别采用六面砧和金刚石对顶砧装置详细研究了RbCr_(3)As_(3)的电输运和晶体结构在高压下的演化规律.研究结果表明,随着压力增加T_c单调降低,7 GPa时下降到~2 K;μ_(0)H_(c2)(0)也随加压而逐渐减小,但在研究的压力范围内(0-7 GPa)仍高于μ_(0)H_(P)^(BCS)和轨道极限(μ_(0)H_(c2)^(orb)(0)),这与K_(2)Cr_(3)As_(3)在高压下μ_(0)H_(c2)(0)迅速减小至低于μ_(0)H_(P)^(BCS)的趋势明显不同.高压XRD结果显示在0-8.5 GPa范围内RbCr_(3)As_(3)没有发生结构相变,a轴和c轴分别缩短~8.3%和~2.4%,表现出较强各向异性的压缩行为.通过对比A_(2)Cr_(3)As_(3)与ACr_(3)As_(3)体系的高压调控规律,我们讨论了化学压力和物理压力对这两类Cr基超导体物性的不同影响.
Cr-based unconventional superconductors discovered in recent years have gained intensive attention due to their unique crystal structure and fascinating physical properties,which have become one of the hot topics in the field of superconductivity research.A_(2)Cr_(3)As_(3)(A=K,Rb,Cs)is the first Cr-based superconducting system at ambient pressure,and the related ACr_(3)As_(3) superconductors with similar quasi-one-dimensional structure can be obtained by chemically removing one of the A ions in A_(2)Cr_(3)As_(3).At ambient pressure,the superconducting transition temperature(Tc)of RbCr_(3)As_(3) can reach~7.3 K,and its upper critical field(μ_(0)H_(c2)(0))also far exceeds the Pauli limit(μ_(0)H_(P)^(BCS)).As a continuation of previous high-pressure studies on A_(2)Cr_(3)As_(3),herein,we further investigate the detailed transport properties and the crystal structure of RbCr_(3)As_(3) under high pressures using the cubic anvil cell and diamond anvil cell,respectively.The findings reveal that its Tc gradually decreases from~7.3 K at ambient pressure to~2 K at 7 GPa.Meanwhile,μ_(0)H_(c2)(0)also gradually decreases with increasing pressure but is still higher thanμ_(0)H_(P)^(BCS) and the orbitallimitingμ_(0)H_(c2)^(orb)(0)in the studied pressure range(0-7 GPa).This is in sharp contrast to K2Cr_(3)As_(3),which exhibits a rapid decrease ofμ_(0)H_(c2)(0)to belowμ_(0)H_(P)^(BCS) under high pressures.The high-pressure X-ray diffraction results reveal no structural phase transition up to 8.5 GPa,but the anisotropic compression with the a and c axes decreased by~8.3%and~2.4%,respectively.By comparison of the high-pressure results of A_(2)Cr_(3)As_(3) and ACr_(3)As_(3) systems,we also discuss the different effects of chemical pressure and physical pressure on the physical properties of these two types of Cr-based superconductors.
作者
刘子儀
穆青隔
任治安
孙建平
程金光
LIU ZiYi;MU QingGe;REN ZhiAn;SUN JianPing;CHENG JinGuang(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China)
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2023年第12期228-236,共9页
Scientia Sinica Physica,Mechanica & Astronomica
基金
国家重点研发计划(编号:2022YFA1403900,2021YFA1400200)
国家自然科学基金(编号:12025408,12174424,11921004)
中国科学院青年创新促进会项目(编号:2023007)
中国博士后科学基金(编号:2022M723354,2023T160676)资助。
