Magneto-structural phase transitions in epitaxial FeRh films: Insights from structural and magnetic microscopy

Speaker: David Keavney, Argonne National Laboratory
Date & Time: Wednesday May 24 at 11:00 AM
Location: AMPEL 311
Local Contact: Andrea Damascelli
Intended Audience:

In materials where structural, magnetic, or electronic degrees of freedom are coupled, rich phase diagrams and potentially useful driven phase transitions can be the result. One such material is the ordered alloy Fe₅₀Rh₅₀, which displays a magneto-structural phase transition at ~375 K. This transition is characterized by a ~1% lattice expansion and a flip from the low temperature antiferromagnetic to the high temperature ferromagnetic phase. We have followed this transition with a combination of high-resolution structural and magnetic imaging, revealing details of the domain nucleation and growth. We have also used soft and hard x-ray magnetic spectroscopies to examine the development of the Fe and Rh moments during the transition. We find that the domain size in both the heating and cooling transitions follows an unexpected 2^nd order-like temperature dependence. In addition, the spectroscopy studies reveal that the development of the Rh moment and the reordering of the Fe moments may not occur simultaneously.