Fig. 2

(A) Layout of the FeRh sample, starting at a 500-µm square down to 1-µm square, each with a thickness of 200 nm. (B) VSM measurements of magnetic moment during a temperature sweep at 1 T external field. The majority of the signal comes from the two largest squares. The high-moment state is considered ON for MRI, and low-moment state is considered OFF. (C) Optical image of a selected 10-µm square (red-circled in A), with a few minor defects. (D) Atomic force microscopy obtained topography image of the same square at 88 °C; (E) corresponding magnetic force microscopy images with increasing temperature. The change from AF (light areas) to FM (dark areas) phase takes place during heating. Distortion of the square shape due to thermal drift of the sample stage was corrected using the Gwyddion program^19,20.