The surface magnetization of Fe3GeTe2 was examined by low-energy electron microscopy (LEEM) using an off-normal incidence electron beam. We found that the 180o domain walls are of Bloch type. Temperature-dependent LEEM measurements yield a surface magnetization with a surface critical exponent β1 = 0.79 +/- 0.02. This result is consistent with surface magnetism in the 3D semi-infinite Heisenberg (β1 = 0.84 +/- 0.01) or Ising (β1 = 0.78 +/- 0.02) models, which is distinctly different from the bulk exponent (β = 0.34 +/- 0.07). The measurements reveal the power of LEEM with a tilted beam to determine magnetic domain structure in quantum materials. Single crystal diffraction measurements reveal inversion symmetry-breaking weak peaks and yield space group P-6m2. This Fe site defect-derived loss of inversion symmetry enables the formation of skyrmions in this Fe3GeTe2 crystal.
@article{arxiv.2409.03565,
title = {Surface Magnetism in Fe$_3$GeTe$_2$ Crystals},
author = {T. A. Tyson and S. Amarasinghe and AM M. Abeykoon and R. Lalancette and S. K. Du and X. Fang and S. -W. Cheong and A. Al-Mahboob and J. T. Sadowski},
journal= {arXiv preprint arXiv:2409.03565},
year = {2024}
}