Spatially resolved ultrafast magnetic dynamics launched at a complex-oxide hetero-interface

TL;DR

This study demonstrates that ultrafast infrared light pulses can induce a magnetic phase transition across a hetero-interface in a complex oxide, with a propagating melt front observed via femtosecond soft X-ray diffraction.

Contribution

It introduces a method to dynamically control magnetic order at hetero-interfaces using light-induced lattice deformations, revealing a propagating magnetic melt front.

Findings

Magnetic order melting is initiated at the hetero-interface.

A magnetic melt front propagates into the NdNiO3 film.

Propagation speed suggests an electronically driven process.

Abstract

Static strain in complex oxide heterostructures has been extensively used to engineer electronic and magnetic properties at equilibrium. In the same spirit, deformations of the crystal lattice with light may be used to achieve functional control across hetero-interfaces dynamically. Here, by exciting large amplitude infrared-active vibrations in a LaAlO3 substrate we induce magnetic order melting in a NdNiO3 film across a hetero-interface. Femtosecond Resonant Soft X-ray Diffraction is used to determine the spatial and temporal evolution of the magnetic disordering. We observe a magnetic melt front that grows from the substrate interface into the film, at a speed that suggests electronically driven propagation. Light control and ultrafast phase front propagation at hetero-interfaces may lead to new opportunities in optomagnetism, for example by driving domain wall motion to transport information across suitably designed devices.