Unveiling a Novel Insulator-to-Metal Transition in La_(N)iO_(4+δ):Challenging High-Temperature Superconductivity Claimed for Single-Layer Lanthanum Nickelates  

作　　者：Yunqi Ji Xiaohan Wang Xiaohe Li Wenting Tang Xinyang Li Xin Wang Fangfei Li Liang Li Qiang Zhou 吉云奇;王晓晗;李晓赫;唐雯婷;李新阳;王鑫;李芳菲;李亮;周强(Synergetic Extreme Condition User Facility,State Key Laboratory of Superhard Materials,College of Physics,Jilin University,Changchun 130012,China)

机构地区：[1]Synergetic Extreme Condition User Facility,State Key Laboratory of Superhard Materials,College of Physics,Jilin University,Changchun 130012,China

出　　处：《Chinese Physics Letters》2024年第9期93-106,共14页中国物理快报（英文版）

基　　金：supported by the National Key Research and Development Program of China(Grant No.2023YFF0804100);the National Natural Science Foundation of China(Grant Nos.12274168,12074141,and 42102030);Jilin Provincial Science and Technology Development Project(Grant Nos.20210402054GH and 20220101011JC);the Program for Jilin University Science and Technology Innovative Research Team(Grant No.2021-TD-05);the support from the Fundamental Research Funds for the Central Universities;National Major Science Facility Synergetic Extreme Condition User Facility Achievement Transformation Platform Construction(Grant No.2021FGWCXNLJSKJ01)。

摘　　要：La_(2)NiO_(4)has a similar structure to La_(2)CuO_(4)and was proposed as a high-temperature superconductor based on magnetic-moment measurements decades ago.Nevertheless,with the exception for electrical resistance drop behavior of about 4 orders of magnitude that is claimed to originate from the superconductivity ever observed in Sr-doped La_(N)iO_(4),most electrical data reported to date in La_(N)iO_(4)system exhibit a trivial insulating ground state.Here,we definitively identify the similar electrical resistance drop behavior of more than 3 orders of magnitude in La_(2)NiO_(4+δ).However,our extensive investigations reveal that this phenomenon is a novel insulatorto-metal transition,distinct from superconductivity.Intriguingly,compared to the weak magnetic-field effects,pressure can significantly suppress the transition and transform from the metallic to an insulating ground state,accompanied by an isostructural phase transition.Our work not only elucidates the fundamental properties of the metallic conducting ground state in La_(N)iO_(4)+δ,but also critically challenges the notion of superconductivity in single-layer lanthanum nickelates.

关 键 词：RESISTANCE electrical METALLIC 

分 类 号：O469[理学—凝聚态物理]