Beschreibung
The Fe$_3$O$_4$/Nb:STO system has garnered significant attention due to its potential applications in spintronics and memristors. We present an investigation of a 30 nm Fe$_3$O$_4$ thin film deposited on a Nb-doped SrTiO$_3$ (Nb:STO) substrate using Polarized Neutron Reflectometry (PNR) and X-ray Reflectometry (XRR) at low temperatures. Around 105K, Nb:STO undergoes an antiferrodistortive transition, and the resulting faceting induces extra strain on the Fe$_3$O$_4$ films, and also affects the resolution and interpretation of PNR measurements [1]. Fe$_3$O$_4$, known for its Verwey transition around 120 K, exhibits changes in electronic conductivity and magnetic properties as the temperature passes through T$_V$ due to structural changes from cubic to monoclinic.
Our study reveals that low temperatures induce notable modifications in the roughness and density of the Fe$_3$O$_4$ film, driven by the transitions in both the Nb:STO substrate and the Fe$_3$O$_4$ film itself. The Verwey transition in Fe$_3$O$_4$ leads to marked changes in its magnetic profile, as observed through variations in the magnetic scattering length density.
These findings highlight the complex interplay between the transitions in Fe$_3$O$_4$ and Nb:STO, providing insights for the development of advanced memory and spintronic devices.
[1] Hoppler et al,PRB 78, 134111 (2008)
