Andreev reflection in superconducting state of pressurized La_(3)Ni_(2)O_(7)  

作　　者：Cong Liu Mengwu Huo Huan Yang Qing Li Yingjie Zhang Zhening Xiang Meng Wang Hai-Hu Wen 

机构地区：[1]National Laboratory of Solid State Microstructures and Department of Physics,Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China [2]Center for Neutron Science and Technology,Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices,School of Physics,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2025年第4期180-188,共9页中国科学:物理学、力学、天文学(英文版)

基　　金：supported by the National Key R&D Program of China(Grant Nos.2022YFA1403201,and 2023YFA1406500);the National Natural Science Foundation of China(Grant Nos.12494591,11927809,12425404,and 123B2055)。

摘　　要：The discovery of superconductivity with T_(c)above 77 K in pressurized La_(3)Ni_(2)O_(7)has stimulated enormous interest in the field of unconventional superconductivity.A recent experiment in La_(2)Pr Ni_(2)O_(7)has shown that the superconducting volume is close to100%.Because the superconductivity can only be achieved under high pressures,many intrinsic properties,such as the superconducting gaps,have not been measured yet.We report the Andreev reflection measurement of pressurized La_(3)Ni_(2)O_(7)with the onset superconducting transition temperature at about 77 K.Our data reveal a clear peak of differential conductivity near zero bias in the tunneling spectrum;and appear also are some temperature-dependent steps that may reflect other superconducting gaps.Calculations based on the Blonder-Tinkham-Klapwijk model with multiple components can roughly fit the data,and the central peak can be fitted with a d-wave gap with a magnitude of about 9 meV,and other two s-wave gaps at about 16 and 26 meV.The latter two large gaps are determined from the enhanced steps of the differential conductivity,which may have other origins.Our results reveal possible evidence of a sign-reversal gap and multi-component features of the superconducting gaps in the nickelate 327 systems.

关 键 词：nickelate superconductor La_(3)Ni_(2)O_(7) point contact spectrum sign-reversal gap multigap superconductor 

分 类 号：O76[理学—晶体学]