液氮温区镍氧化物高温超导体的发现  

Discovery of high-T_(c) superconductivity in a nickelate

作　　者：王猛 WANG Meng(Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices,Center for Neutron Science and Technology,School of Physics,Sun Yat-Sen University,Guangzhou 510275,China)

机构地区：[1]中山大学物理学院中子科学与技术中心、广东省磁电物性分析与器件重点实验室,广州510275

出　　处：《物理》2023年第10期663-671,共9页Physics

基　　金：国家自然科学基金(批准号:12174454);广东省磁电物性分析与器件重点实验室(批准号:2022B1212010008)资助项目;广东省基础与应用基础研究区域联合基金-重点项目(批准号:2021B1515120015)。

摘　　要：非常规超导材料探索和机理研究是物理学中重要的研究内容和科学问题。目前主要的非常规超导体材料包括重费米子超导体、铜氧化物高温超导体和铁基超导体。其中只有铜氧化物超导临界温度高于液氮沸点77 K,处于液氮温区。镍氧化物与铜氧化物具有相似的材料结构体系,其中+1价镍离子与+2价铜离子具有相同的电子填充数,是此前研究人员探索超导电性的重点。具有钙钛矿结构单元、双镍氧层的La3Ni2O7中镍的价态为+2.5,常压下呈现顺磁性的金属态。近期作者在14 GPa压力下的La3Ni2O7单晶样品中发现了高达80 K的超导临界温度,超出此前理论预期。文章将简要介绍非常规超导材料体系的研究历史、La3Ni2O7单晶样品的生长方法、常压下的物理性质和高压下的结构表征、以及通过电学和磁性测量对超导电性的确认。Exploration of unconventional superconductors and elucidation of their mechanism have been important frontiers in condensed matter physics for more than 40 years.Heavy fermi superconductors,copper oxide high-Tc superconductors,and iron-based superconductors are three large families of unconventional superconductors.Cuprates are the only family that hosts high superconducting transition temperatures above the boiling point of nitrogen at ambient pressure.Nickel oxides with Ni+are expected to show unconventional superconductivity due to the similarity of the electronic configurations of Cu^(2+)and Ni^(+).Recently,we discovered superconductivity under 14 GPa at 80 K in a bilayer nickelate La_(3)Ni_(2)O_(7) with an average valent state of Ni^(2.5+).In this paper,we will describe the verification of superconductivity by electronic and magnetic measurements,as well as the determination of the crystal structure of La_(3)Ni_(2)O_(7) under pressure.The obvious difference of the magnetic ground state of La3Ni2O7 from that of copper oxide and iron-based superconductors may be vital for elucidating the mechanism of unconventional superconductivity.

关 键 词：非常规超导 高温超导 镍氧化物 

分 类 号：O511.3[一般工业技术—材料科学与工程]