摘要
Perovskite-structured nickelates,ReNiO_(3)(Re=rare earth),have long garnered significant research interest due to their sharp and highly tunable metal-insulator transitions(MITs).Doping the parent compound ReNiO_(3)with alkaline earth metal can substantially suppress this MIT.Recently,intriguing superconductivity has been discovered in doped infinite-layer nickelates(ReNiO_(2)),while the mechanism behind A-site doping-suppressed MIT in the parent compound ReNiO_(3)remains unclear.To address this problem,we grew a series of Nd_(1−x)Sr_(x)NiO_(3)(NSNO,x=0–0.2)thin films and conducted systematic electrical transport measurements.Our resistivity and Hall measurements suggest that Sr-induced excessive holes are not the primary reason for MIT suppression.Instead,first-principles calculations indicate that Sr cations,with larger ionic radius,suppress breathing mode distortions and promote charge transfer between oxygen and Ni cations.This process weakens Ni–O bond disproportionation and Ni^(2+)/Ni^(4+)charge disproportionation.Such significant modulations in lattice and electronic structures convert the ground state from a charge-disproportionated antiferromagnetic insulator to a paramagnetic metal,thereby suppressing the MIT.This scenario is further supported by the weakened MIT observed in the tensile-strained NSNO/SrTiO_(3)(001)films.Our work reveals the A-side doping-modulated electrical transport of perovskite nickelate films,providing deeper insights into novel electric phases in these strongly correlated nickelate systems.
基金
supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406404 and 2020YFA0309100)
the National Natural Science Foundation of China(Grant Nos.12074365,12374094,12304153,U2032218,and 11974326),the National Natural Science Foundation of China(Grant No.12274120)
CAS Project for Young Scientists in Basic Research(Grant No.YSBR-084)
the Fundamental Research Funds for the Central Universities(Grant Nos.WK9990000102 and WK2030000035)
Anhui Provincial Natural Science Foundation(Grant No.2308085MA15)
Hefei Science Center CAS Foundation(Grant Nos.2021HSC-CIP017 and 2016HSC-IU06)
the China Postdoctoral Science Foundation(Grant No.2022M713060)
the starting funds from Northwest University
support from the Vienna Scientific Cluster(VSC)for the first-principles calculations。
