Covalent mixing in the two-dimensional ferromagnet CrSiTe₃ evidenced by magnetic x-ray circular dichroism

Journal article : Letter

The low-temperature electronic structure of the van der Waals ferromagnet CrSiTe3 has been investigated. This ferromagnetic semiconductor has a magnetic bulk transition temperature of 33 K, which can reach up to 80 K in single- and few-layer flakes. X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements, carried out at the Cr L_2,3 and Te M_b edges on in vacuo cleaved single crystals, give strong evidence for hybridization-mediated super-exchange between the Cr atoms. The observed chemical shift in the XAS, as well as the comparison of the XMCD with the calculated Cr L_2,3 multiplet spectra, confirm a strongly covalent bond between the Cr 3d(e_g) and Te 5p states. Application of the XMCD sum rules gives a non-vanishing orbital moment, supporting a partial occupation of the e_g states, apart from the t_2g. Also, the presence of a non-zero XMCD signal at the Te Mb edge confirms a Te 5p spin polarization due to mixing with the Cr e_g bonding states. The results strongly suggest that superexchange, instead of the previously suggested single ion anisotropy, is responsible for the low-temperature ferromagnetic ordering of 2D materials such as CrSiTe₃ and CrGeTe₃. This demonstrates the interplay between electron correlation and ferromagnetism in insulating two-dimensional materials.

Authors: Achinuq, B; Fujita, R; Xia, W; Guo, Y; Bencok, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: physica status solidi (RRL) - Rapid Research Letters
• Volume: 16
• Issue: 4
• Article number: 2100566
• Publication date: 2021-12-30
• Acceptance date: 2021-12-16
• DOI: 10.1002/pssr.202100566
• EISSN: 1862-6270
• ISSN: 1862-6254
• Language: English
• Keywords: FFR
• Subtype: Letter