# Emergent magnetic state in (111)-oriented quasi-two-dimensional spinel oxides

## TL;DR

This study uncovers a novel magnetic state in ultrathin (111)-oriented CoCr2O4 spinel films, showing enhanced magnetization and a new Yafet-Kittel type ordering due to quantum confinement effects.

## Contribution

It reveals the emergence of a Yafet-Kittel type magnetic order in ultrathin spinel films, a state not observed in bulk materials.

## Key findings

- Enhanced magnetization in ultrathin films
- Long-range ferromagnetic ordering of Co and Cr spins
- Yafet-Kittel type magnetic ground state

## Abstract

We report on the emergent magnetic state of (111)-oriented CoCr2O4 ultrathin films sandwiched by Al2O3 in the quantum confined geometry. At the two-dimensional crossover, polarized neutron reflectometry reveals an anomalous enhancement of the total magnetization compared to the bulk value. Synchrotron x-ray magnetic circular dichroism (XMCD) demonstrates the appearance of long-range ferromagnetic ordering of spins on both Co and Cr sublattices. Brillouin function analyses further corroborates that the observed phenomena are due to the strongly altered magnetic frustration, manifested by the onset of a Yafet-Kittel type ordering as the new ground state in the ultrathin limit, which is unattainable in the bulk.