Tailoring Emergent Magnetic Moment in La$_{0.7}$Sr$_{0.3}$MnO$_3$-Bi$_2$Te$_3$ Heterostructures via Interfacial Reconstructions

TL;DR

This study demonstrates how interfacial reconstructions in La$_{0.7}$Sr$_{0.3}$MnO$_3$-Bi$_2$Te$_3$ heterostructures induce emergent magnetic phases and unconventional hysteresis behaviors at room temperature, controlled by interface engineering.

Contribution

It reveals that interface reconstructions can stabilize new magnetic phases and alter magnetic hysteresis in oxide-topological insulator heterostructures, offering a pathway for magnetic property control.

Findings

Reconstructed interfaces stabilize a secondary magnetic phase.

Unconventional self-crossing magnetic hysteresis loops observed.

Enhanced saturation magnetization with tellurium seed layer.

Abstract

We report emergent magnetic behavior in heterostructures composed of (111)-oriented La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) and (00$l$)-oriented Bi$_2$Te$_3$ (BT), controlled by interfacial reconstructions. When BT is deposited directly onto LSMO, an intermediate interfacial layer forms between the two materials. Polarized Neutron Reflectometry modeling reveals that this reconstructed region stabilizes a secondary magnetically ordered phase that is coupled to the underlying ferromagnetic LSMO layer. As a consequence, the heterostructures exhibit unconventional self-crossing magnetic hysteresis loops at room temperature, characterized by a reversal of the net magnetization at low applied fields. In contrast, the introduction of a tellurium seed layer results in a sharper LSMO-BT interface, while preserving the anomalous hysteresis behavior and enhancing the saturation magnetization. Element-specific X-ray absorption spectroscopy suggests that the emergent magnetic phase originates from the chemical reconstruction of manganese species. These results demonstrate that interface engineering in magnetic oxide-topological insulator heterostructures provides a pathway to control emergent magnetic coupling and emergent magnetic states in oxide-topological insulator heterostructures.