Magnetism and Conductivity Along Structural Domain Walls of SrTiO3

Abstract

The interface between the oxide insulators LaAlO 3 and SrTiO 3 (LAO/STO) hosts a two-dimensional electron gas. The combination of interfacial conductivity and superconductivity at ultra-low temperatures with the physical phenomena of the oxide parent materials has fueled extensive research in the field since its discovery in 2004. Scanning superconducting quantum interference device (SQUID) measurements have shown that structural domain walls, formed below 105 K, modulate the current flow at the interface and recently revealed weak magnetic signals along the same domain structure. Here we use scanning SQUID to investigate the temperature dependence of different electronic properties of the LAO/STO interface. We find correlation between magnetism and conductivity, which are both spatially modulated on the domain structure. This data suggests a possible relation between the populations of electrons participating in each order.

Current vortices and magnetic fields driven by moving polar twin boundaries in ferroelastic materials

“…For example, enhancing the flexoelectric polarization by increasing the ferroelastic shear angle produces stronger magnetic fields. Magnetic fields produced by the fast movement of our ferroelastic twins are much larger than the recent investigations on the heterogeneous structures near LaAlO 3 and SrTiO 3 (LAO/STO) interfaces 24,25 . In these observations, the occurrences of the magnetic signals were explained in terms of the couplings between lattices and spins or free electrons near the LAO/STO interfaces or the domain walls below T_c = 105 K for SrTiO 3 .…”

“…4a, b. Simultaneously the magnetic field is measured using a superconducting quantum interference device (SQUID) 24,25 . This experimental arrangement is similar to that proposed to measure the magnetization in a moving ferroelectric domain wall 26 , while has a major difference.…”

“…Among these functional properties, magnetism has rarely been reported to emerge from twin walls. Although some ideas have been proposed to explore the possible magnetisms inside ferroelastic heterostructures 24,25 , the corresponding magnetic signals were too weak for practical applications or even to be measured experimentally. Recently, within the framework of dynamical multiferroicity 26,27 , magnetic signals were shown to emerge from inside moving ferroelectric domain walls.…”