三角晶格自旋液体候选材料NaYbSe_(2)在高压下的超导转变  

Pressure-induced superconductivity in triangular lattice spin liquid candidate NaYbSe_(2)

作　　者：郭琳[1] 杨小帆 程二建 泮炳霖 朱楚楚 李世燕[1] Guo Lin;Yang Xiao-Fan;Cheng Er-Jian;Pan Bing-Lin;Zhu Chu-Chu;Li Shi-Yan(State Key Laboratory of Surface Physics,Department of Physics,Fudan University,Shanghai 200438,China)

机构地区：[1]复旦大学物理系,应用表面物理国家重点实验室,上海200438

出　　处：《物理学报》2023年第15期236-241,共6页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2022YFA1402203);国家自然科学基金(批准号:12034004)资助的课题.

摘　　要：量子自旋液体是一种由于自旋阻挫直到零温都不能形成磁有序的新奇量子态,并且和高温超导密切相关,因此,能否通过压力或化学掺杂等方式在量子自旋液体材料中调控出超导态甚至高温超导是一个重要的物理问题.二维三角晶格稀土硫属化合物NaYbCh_(2)(Ch=O,S,Se)在比热、核磁共振、中子散射等实验中未出现长程磁有序,被认为可能具有量子自旋液体基态.本文研究了NaYbCh_(2)(Ch=Se,S,O)在压力下的电输运行为.对于NaYbSe_(2),当压力加到26.9 GPa时出现超导转变,表现出零电阻行为,其超导转变温度(Tc)约为5.6 K,并且直到45 GPa都保持基本不变,得出了其超导转变温度对压力的相图;对于NaYbS2,压力使其室温电阻从10 GPa下10^(11)Ω量级降低到67 GPa的10 Ω量级,然而其电阻随温度行为没有出现金属性,也没有发生超导转变;而对于NaYbO2,其从常压到60 GPa高压一直保持完全绝缘态,没有可观测的电阻.Quantum spin liquid is an exotic state without magnetic order down to zero-temperature due to spin frustration,which is closely related to high temperature superconductivity.Therefore,an important issue arises whether the quantum spin liquid can be adjusted into a superconductor,even high-Tc superconductor,by using pressure or chemical doping.Rear-earth chalcogenides NaYbCh_(2)(Ch=O,S,Se),consisting of planar triangular lattice,exhibit no long-range magnetic order down to the lowest measured temperatures in specific heat,nuclear magnetic resonance,and neutron scattering,and are considered as a quantum spin liquid candidate.Here we investigate the electrical transport properties of NaYbCh_(2)(Ch=O,S,Se)under high pressures.For NaYbSe_(2),zero-resistance behavior is observed at 26.9 GPa,showing that the superconductivity comes into being.The superconducting transition temperature(Tc)is around 5.6 K at 26.9 GPa and robust against pressure till 45 GPa.The phase diagram of Tc versus pressure for NaYbSe_(2) is constructed.For NaYbS_(2),the room temperature resistance decreases from the order of 10^(11) Ω at 10 GPa to 10 Ω at 67 GPa.However,neither superconductivity nor insulator-metal transition is observed.Additionally,the NaYbO_(2) keeps insulating and the resistance is too large to be detected in a pressure range of 0–60 GPa.

关 键 词：量子自旋液体 高压 电输运 

分 类 号：O413[理学—理论物理] O511[理学—物理]