Itinerant ferromagnetism mediated by giant spin polarization of metallic ligand band in van der Waals magnet Fe₅GeTe₂

There is a growing interest in searching for new magnetism in van der Waals (vdW) compounds. In particular, one of the most important issues is to understand the mechanism of low-dimensional itinerant ferromagnetism. Very recent studies on ferromagnetic insulators of vdWs suggest that spin polarization of nonmagnetic ligands induced by hybridization with magnetic elements plays an important role in ferromagnetism[1,2]. In this study, we focused on vdW ferromagnetic metals at room-temperature Fe₅GeTe₂[3] and investigated element-specific electronic states by soft X-ray angle-resolved photoemission spectroscopy (SX-ARPES) and soft X-ray magnetic circular dichroism (XMCD).
Experiments were performed at SPring-8 BL25SU and BL23SU, respectively. We reveal that the Fe 3d state reflects a metallic electronic state. On the other hand, distinct XMCD spectra were also observed in the non-magnetic Te/Ge. This indicates that the spin polarization is induced in Te/Ge by the hybridization with Fe 3d orbitals. We present SX-ARPES results and discuss the role of spin-polarized non-magnetic elements in vdW ferromagnetic metals.
[1] K. Wang et al., Phys. Chem. Chem. Phys., 21, 9597 (2019). [2] D.-H. Kim et al., Phys. Rev. Lett., 122, 207201 (2019). [3] A. F. May et al., ACS Nano, 13, 4436 (2019).