Strain induced anisotropy in liquid phase epitaxy grown nickel ferrite on magnesium gallate substrates

Ying Liu; Peng Zhou; Sudhir Regmi; Rao Bidthanapally; Maksym Popov; Jitao Zhang; Wei Zhang; Michael R Page; Tianjin Zhang; Arunava Gupta; Gopalan Srinivasan

doi:10.1038/s41598-022-10814-8

Strain induced anisotropy in liquid phase epitaxy grown nickel ferrite on magnesium gallate substrates

Sci Rep. 2022 Apr 29;12(1):7052. doi: 10.1038/s41598-022-10814-8.

Authors

Ying Liu^{1

2}, Peng Zhou², Sudhir Regmi³, Rao Bidthanapally¹, Maksym Popov⁴, Jitao Zhang⁵, Wei Zhang¹, Michael R Page⁶, Tianjin Zhang², Arunava Gupta³, Gopalan Srinivasan⁷

Affiliations

¹ Department of Physics, Oakland University, Rochester, MI, 48309, USA.
² Department of Materials Science and Engineering, Hubei University, Wuhan, 430062, China.
³ Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, AL, 3548, USA.
⁴ Faculty of Radiophysics, Electronics and Computer Systems, Taras Shevchenko National University of Kyiv, Kyiv, 01601, Ukraine.
⁵ College of Electrical and Information Engineering, Zhengzhou University of Light Industry, Zhengzhou, 450002, China.
⁶ Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH, 45433, USA.
⁷ Department of Physics, Oakland University, Rochester, MI, 48309, USA. srinivas@oakland.edu.

Abstract

This work focuses on the nature of magnetic anisotropy in 2.5-16 micron thick films of nickel ferrite (NFO) grown by liquid phase epitaxy (LPE). The technique, ideal for rapid growth of epitaxial oxide films, was utilized for films on (100) and (110) substrates of magnesium gallate (MGO). The motivation was to investigate the dependence of the growth induced anisotropy field on film thickness since submicron films of NFO were reported to show a very high anisotropy. The films grown at 850-875 C and subsequently annealed at 1000 C were found to be epitaxial, with the out-of-plane lattice constant showing unanticipated decrease with increasing film thickness and the estimated in-plane lattice constant increasing with the film thickness. The uniaxial anisotropy field H_σ, estimated from X-ray diffraction data, ranged from 2.8-7.7 kOe with the films on (100) MGO having a higher H_σ value than for the films on (110) MGO. Ferromagnetic resonance (FMR) measurements for in-plane and out-of-plane static magnetic field were utilized to determine both the magnetocrystalline the anisotropy field H₄ and the uniaxial anisotropy field H_a. Values of H₄ range from -0.24 to -0.86 kOe. The uniaxial anisotropy field H_a was an order of magnitude smaller than H_σ and it decreased with increasing film thickness for NFO films on (100) MGO, but H_a increased with film thickness for films on (110) MGO substrates. These observations indicate that the origin of the induced anisotropy could be attributed to several factors including (i) strain due to mismatch in the film-substrate lattice constants, (ii) possible variations in the bond lengths and bond angles in NFO during the growth process, and (iii) the strain arising from mismatch in the thermal expansion coefficients of the film and the substrate due to the high growth and annealing temperatures involved in the LPE technique. The LPE films of NFO on MGO substrates studied in this work are of interest for use in high frequency devices.

Abstract

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