Anomalous magnetic ground state in LaAlO3/SrTiO3 interface probed by transport through nanowires

TL;DR

This study investigates the magnetic properties of LaAlO3/SrTiO3 nanowires at ultra-low temperatures, revealing a complex magnetic order with domain structures that coexist with superconductivity, using transport measurements under high magnetic fields.

Contribution

It provides new insights into the magnetic ground state of LaAlO3/SrTiO3 interfaces, highlighting the presence of domain-based magnetic order distinct from simple ferromagnetism.

Findings

Magnetic order vanishes at T_Curie = 954 mK.

Hysteresis loops observed indicating magnetic domains.

Magnetic effects are distinguishable from superconductivity in nanowires.

Abstract

Resistance as a function of temperature down to 20mK and magnetic fields up to 18T for various carrier concentrations is measured for nanowires made from the SrTiO3/LaAlO3 interface using a hard mask shadow deposition technique. The narrow width of the wires (of the order of 50nm) allows us to separate out the magnetic effects from the dominant superconducting ones at low magnetic fields. At this regime hysteresis loops are observed along with the superconducting transition. From our data analysis we find that the magnetic order probed by the giant magnetoresistance (GMR) effect vanishes at TCurie = 954 mK. This order is not a simple ferromagnetic state but consists of domains with opposite magnetization having a preferred in-plane orientation.