Magnetic anisotropy in the near-stoichiometric van der Waals ferromagnet Fe 3 GeTe 2
Researchers used electron spin resonance (ESR) across various frequencies, temperatures, and magnetic fields to study single-crystalline Fe3.03±0.03GeTe2. They found it is an easy-axis ferromagnet with strong uniaxial magnetocrystalline anisotropy along the c-direction, characterized by a large magnon gap. The study shows that small changes in iron content significantly alter the magnon gap, highlighting extreme sensitivity to stoichiometry.