1. Surface Magnetism in Fe$_3$GeTe$_2$ Crystals
- Author
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Tyson, T. A., Amarasinghe, S., Abeykoon, AM M., Lalancette, R., Du, S. K., Fang, X., Cheong, S. -W., Al-Mahboob, A., and Sadowski, J. T.
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
The surface magnetization of Fe$_3$GeTe$_2$ was examined by low-energy electron microscopy (LEEM) using an off-normal incidence electron beam. We found that the 180$^o$ domain walls are of Bloch type. Temperature-dependent LEEM measurements yield a surface magnetization with a surface critical exponent $\beta$1 = 0.79 +/- 0.02. This result is consistent with surface magnetism in the 3D semi-infinite Heisenberg ($\beta$1 = 0.84 +/- 0.01) or Ising ($\beta$1 = 0.78 +/- 0.02) models, which is distinctly different from the bulk exponent ($\beta$ = 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 Fe$_3$GeTe$_2$ crystal.
- Published
- 2024