The Evolution of Magnetism in a Thin Film Pyrochlore Ferromagnetic Insulator

TL;DR

This study reports the synthesis of ultrathin pyrochlore Y2V2O7 films, revealing how magnetic properties and anisotropy evolve with thickness and strain, crucial for future magnonic device applications.

Contribution

First synthesis of Y2V2O7 thin films on Y2Ti2O7 substrates, demonstrating thickness-dependent magnetic transition temperatures and anisotropy changes due to strain effects.

Findings

Films remain insulating ferromagnets with Tc up to 68 K.

Magnetic anisotropy shifts from in-plane to out-of-plane with decreasing thickness.

Strain influences magnetic properties and enables tunable magnon topology.

Abstract

The pyrochlore vanadates are compelling candidates for next-generation dissipationless devices. Lu2V2O7 and Y2V2O7 are ferromagnetic insulators (Tc ~ 70 K) that are believed to exhibit the magnon Hall effect and are expected to host topological magnons. Their completely dissipationless magnon edge states could be harnessed to realize low-power information transport in spintronic or magnonic devices. As a crucial step in the realization of devices, we synthesize the first thin films of pyrochlore Y2V2O7 on isostructural Y2Ti2O7 substrates and explore the evolution of their magnetic properties down to the ultrathin limit. All films are insulating ferromagnets with transition temperatures of up to the bulk value (Tc ~ 68 K) that decrease with thickness according to finite-size effects. Our films also exhibit a change in anisotropy from in-plane to out-of-plane easy axis coincident with the development of partial strain relaxation and nonzero magnetic hysteresis in an applied field. This evolution demonstrates the impact of strain on magnetic anisotropy and paves the way to tunable magnon topology.