Ferromagnetic insulating ground states in oxygen deficient La0.8Sr0.2CoO3 <b> − <i>δ</i> </b> films induced by ionic liquid gating

S S. Mo (Engineering Research Center of Micro-nano Optoelectronic Materials and Devices, Ministry of Education; Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, and Department of Physics, Xiamen University 1 , Xiamen 361005,) Y Y. Su T T. Deng (Engineering Research Center of Micro-nano Optoelectronic Materials and Devices, Ministry of Education; Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, and Department of Physics, Xiamen University 1 , Xiamen 361005,) P P. Han (Department of Physics, Beijing Key Lab for Metamaterials and Devices, Capital Normal University 2 , Beijing 100048,) J J. Shi K K. H. L. Zhang (State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University 3 , Xiamen 361005,) M M. Wu (Department of Cell Biology) H H.-Q. Wang (Engineering Research Center of Micro-nano Optoelectronic Materials and Devices, Ministry of Education; Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, and Department of Physics, Xiamen University 1 , Xiamen 361005,) J J. Kang

Abstract

Ferromagnetic (FM) insulators are regarded as promising candidates for next-generation electronic and spintronic devices due to their low power consumption and high processing efficiency. However, achieving FM insulators with high Curie temperatures (Tc) remains a challenge. Here, we report high-Tc FM insulating La0.8Sr0.2CoO3 (LSCO) thin films with oxygen deficiencies, in which the concentration of oxygen vacancy (Vo) is modulated through ionic liquid gating (ILG). An abrupt metal–insulator transition has been observed in LSCO films even at low Vo concentration, which can be attributed to the disorder-dominant electric transport behavior. At high Vo concentrations, the transition from original Co–O octahedral (Oh) to tetrahedral (Td) symmetry opens a bandgap with well-defined band edges, stabilizing the insulating state. These findings provide important insights into the manipulation and design of robust FM insulating ground states in complex oxides via topotactic ILG regulation, offering a viable pathway toward advanced spintronics applications.

Article Details

Volume / Issue Vol. 128, Issue 21
Published May 25, 2026
ISSN 0003-6951
Publisher American Institute of Physics

Journal Info

Applied Physics Letters

American Institute of Physics

ISSN: 0003-6951 Physical Sciences

Authors (9)

S

S. Mo

Engineering Research Center of Micro-nano Optoelectronic Materials and Devices, Ministry of Education; Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, and Department of Physics, Xiamen University 1 , Xiamen 361005,

Y

Y. Su

T

T. Deng

Engineering Research Center of Micro-nano Optoelectronic Materials and Devices, Ministry of Education; Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, and Department of Physics, Xiamen University 1 , Xiamen 361005,

P

P. Han

Department of Physics, Beijing Key Lab for Metamaterials and Devices, Capital Normal University 2 , Beijing 100048,

J

J. Shi

K

K. H. L. Zhang

State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University 3 , Xiamen 361005,

M

M. Wu

Department of Cell Biology

H

H.-Q. Wang

Engineering Research Center of Micro-nano Optoelectronic Materials and Devices, Ministry of Education; Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, and Department of Physics, Xiamen University 1 , Xiamen 361005,

J

J. Kang