Room temperature weak collinear ferrimagnet with symmetry driven, large intrinsic magneto-optic signatures

TL;DR

This paper reports a room-temperature weak ferrimagnetic thin film with symmetry-driven magneto-optic properties, showing potential for high-speed spintronic applications due to its large intrinsic signatures and strain sensitivity.

Contribution

The study provides a symmetry analysis and theoretical calculation of magneto-optic spectra, confirming the coexistence of AFM and FIM phases sharing the same magnetic space group and highlighting their room-temperature properties.

Findings

Good agreement between measured and predicted MOKE spectra.

FIM phase exhibits large optical and transport signatures at room temperature.

Magneto-optic properties are maximized due to intrinsic Berry phase contributions.

Abstract

Here we present a magnetic thin film with a weak ferrimagnetic (FIM) phase above the N\'eel temperature ($T_{N}$ = 240 K) and a non-collinear antiferromagnetic (AFM) phase below, exhibiting a small net magnetisation due to strain-associated canting of the magnetic moments. A long-range ordered FIM phase has been predicted in related materials, but without symmetry analysis. We now perform this analysis and use it to calculate the MOKE spectra in AFM and FIM phases. From the good agreement between the form of the measured and predicted MOKE spectra, we propose the AFM and FIM phases share the magnetic space group C2'/m' and that the symmetry driven magneto-optic and magneto-transport properties are maximised at room temperature in the FIM phase due to the non-zero intrinsic Berry phase contribution present in these materials. A room temperature FIM phase with large optical and transport signatures, as well as sensitivity to lattice strain and magnetic field, has useful prospects for high-speed spintronic applications.