Enhancing the magnetic moment of ferrimagnetic NiCo2O4 via ion irradiation driven oxygen vacancies

Parul Pandey, Yugandhar Bitla, Matthias Zschornak, Mao Wang, Chi Xu, Jörg Grenzer, Dirk Carl Meyer, Yi Ying Chin, Hong Ji Lin, Chien Te Chen, Sibylle Gemming, Manfred Helm, Ying-hao Chu, Shengqiang Zhou

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6 Scopus citations

Abstract

Ion irradiation has emerged as a powerful tool for the efficient control of uniaxial lattice expansion to fine tune and modulate the otherwise inaccessible complex correlated phases in oxide thin-films. We report the fine tuning of the magnetic moment, ferromagnetic-paramagnetic and metal-insulator transition temperatures in the NiCo2O4 inverse-spinel oxide by creating oxygen deficiencies, employing high energy He-ion irradiation. Tailoring of oxygen vacancies and consequently a uniaxial lattice expansion in the out-of-plane direction drives the system toward the increase of the magnetic moment by two-times in magnitude. The magnetic moment increases with the He-ion irradiation fluence up to 2.5 × 1016/cm2. Our results are corroborated well by spin-polarized electronic structure calculations with density functional theory and X-ray absorption spectroscopic data, which show peak-height change and energy shift of Co-L2,3 and Ni-L2,3 edges driven by the oxygen vacancies. These results demonstrate a new pathway of tailoring oxygen vacancies via He-ion irradiation, useful for designing new functionalities in other complex oxide thin-films.

Original languageEnglish
Article number066109
JournalAPL Materials
Volume6
Issue number6
DOIs
StatePublished - 1 Jun 2018

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