We present studies of the magnetic domain structure of UMn2Ge2 single crystals using a home-built low temperature magnetic force microscope. The material has two distinct magnetic ordering temperatures, originating from the Mn and U moments. At room temperature, where the Mn moments dominate, there are flower-like domain patterns similar to those observed in uniaxial ferromagnets. After exposing the sample to a one-tesla magnetic field near 40 K, the evolution of the magnetic domains are imaged through zero-field warming up to 200 K. Near the ordering temperature of the uranium moments a clear change in the domain wall motion is observed. The domain size analysis of the flower-like pattern reveals that the domain structure is consistent with a model of branching domains.
@article{arxiv.1709.05007,
title = {Imaging the magnetic states in an actinide ferromagnet UMn$_2$Ge$_2$},
author = {Xinzhou Tan and Morgann Berg and Jeehoon Kim and Ryan E. Baumbach and Eric D. Bauer and Joe D. Thompson and Filip Ronning and Alex de Lozanne},
journal= {arXiv preprint arXiv:1709.05007},
year = {2018}
}