Disentangling the magneto-optic Kerr effect of manganite epitaxial heterostructures

TL;DR

This study investigates the wavelength-dependent magneto-optic Kerr effect in manganite heterostructures, revealing how layered ferromagnetic components contribute to complex hysteresis features, advancing understanding of magnetic interactions in these materials.

Contribution

It provides a detailed analysis of the Kerr effect in manganite heterostructures, demonstrating how layer-specific contributions cause unique hysteresis features, which was not previously understood.

Findings

Humplike features in Kerr hysteresis loops originate from opposite Kerr rotations of different layers.

Disentangling layer contributions clarifies the origin of complex Kerr signals.

Layer interactions influence magneto-optic responses in heterostructures.

Abstract

Magneto-optic Kerr effect can probe the process of magnetization reversal in ferromagnetic thin films and thus be used as an alternative to magnetometry. Kerr effect is wavelength-dependent and the Kerr rotation can reverse sign, vanishing at particular wavelengths. We investigate epitaxial heterostructures of ferromagnetic manganite, La$_{0.7}$Sr$_{0.3}$Mn$_{0.9}$Ru$_{0.1}$O$_3$, by polar Kerr effect and magnetometry. The manganite layers are separated by or interfaced with a layer of nickelate, NdNiO$_3$. Kerr rotation hysteresis loops of trilayers, with two manganite layers of different thickness separated by a nickelate layer, have intriguing humplike features, when measured with light of 400 nm wavelength. By investigating additional reference samples we disentangle the contributions of the individual layers to the loops: we show that the humps originate from the opposite sense of the Kerr rotation of the two different ferromagnetic layers, combined with the additive behavior of the Kerr signal.