Interfacial and surface magnetism in epitaxial NiCo₂O₄(001)/MgAl₂O₄ films

Authors

• Corbyn Mellinger, University of Nebraska-Lincoln
• Xiao Wang, Bryn Mawr College
• Arjun Subedi, University of Nebraska–LincolnFollow
• Andy T. Clark, Bryn Mawr College
• Takashi Komesu, University of Nebraska - LincolnFollow
• Richard Rosenberg, Argonne National Laboratory
• Peter A. Dowben, University of Nebraska-LincolnFollow
• Xuemei Cheng, Bryn Mawr College
• Xiaoshan S. Xu, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

5-17-2023

Citation

J. Appl. Phys. 133, 195301 (2023); doi: 10.1063/5.0152539

Comments

Used by permission.

Abstract

NiCo₂O₄ (NCO) films grown on MgAl₂O₄ (001) substrates have been studied using magnetometry and x-ray magnetic circular dichroism based on x-ray absorption spectroscopy and spin-polarized inverse photoemission spectroscopy with various thicknesses down to 1.6 nm. The magnetic behavior can be understood in terms of a layer of optimal NCO and an interfacial layer (1.2 ± 0.1 nm), with a small canting of magnetization at the surface. The thickness dependence of the optimal layer can be described by the finite-scaling theory with a critical exponent consistent with the high perpendicular magnetic anisotropy. The interfacial layer couples antiferromagnetically to the optimal layer, generating exchange-spring styled magnetic hysteresis in the thinnest films. The non-optimal and measurement-speed-dependent magnetic properties of the interfacial layer suggest substantial interfacial diffusion.