Interplay between Ferroelasticity, Electron Pairing, and Magnetism in LaAlO₃/SrTiO₃Nanostructures

Abstract: The LaAlO₃/SrTiO₃ interface exhibits a wide range of rich physical properties including superconductivity, electron pairing without superconductivity, magnetism, and spin orbit coupling. However, the microscopic origin of low temperature transport is not well understood. A long-standing question involves the unknown interrelations between structural distortions, electron pairing, and low temperature transport phenomena. In this talk, I will discuss experimental signatures of interplay between ferroelasticity, electron pairing, and magnetism at the LaAlO₃/SrTiO₃ interface.  

I will present low-temperature magnetotransport measurements on quasi-one dimensional (1D), cross-shaped electron waveguides, “nanocrosses”. The crossed geometry (i) allows simultaneous measurement of longitudinal and Hall transport in the 1D regime, and (ii) defines the X, Y and Z ferroelastic domains at the interface. Experimental evidence of an inhomogeneous energy landscape at nanoscale level, interplay between nonlinear Hall effect and electron pairing, and electronic nematic phases such as anisotropic nonlinear Hall resistance are shown at the LAO/STO interface. Ferroelastic domain models for varying spatial orientation of the nanocrosses are proposed. Lastly, the long-range electromechanical nature of gating at the interface is discussed.

The results described here highlight the functional interrelations between ferroelastic domains, electron pairing and magnetism at the LaAlO₃/SrTiO₃ interface and brings forth new insights into the role preformed electron pairs in the overall phase diagram of the LaAlO₃/SrTiO₃ system. These findings provide a step forward in understanding the pairing mechanism and the rich correlated electron physics at the LaAlO₃/SrTiO₃ interface.