Fig. 4

(A) Gradient-echo MR images from a temperature sweep at 4.7T. The signatures of the structures from 500 μm down to 10 μm clearly enlarge after heating to > 50 °C, and then return to baseline during cooling with a lag from the hysteresis as expected. Image resolution here was 150 μm isotropic with 10 ms TE, to get a time resolution of 4 min. (B) Normalized MRI mean signal intensity plot of an ROI around the 200 μm structure. (C) ROIs from the 10–100 μm structures used for the normalized mean intensity plots in (D) The hysteresis curves are as expected for FeRh, although there are some differences in the transition temperature. One of the 10 μm structures is obscured by debris and is not plotted.