Non-collinear Effects and Substrate-mediated Magnetic Interactions in Mn trimers on the GaN (000-1) Surface

DIEGO HUNT; BARRAL MARIA ANDREA; VALERIA FERRARI; ARTHUR SMITH

Conferencia; APS Meeting 2021; 2021

As a pre-cursor tothe formation of 2D MnGaN[1], Mn deposition on GaN(000-1) at 300 Kcan at first lead to a 3x3 trimer structure[2]. Collinear andnon-collinear calculations based on density functional theory arecarried out to elucidate the magnetic ordering of monomers, dimersand trimers of Mn on GaN(000-1) surface. We estimate the magneticanisotropy energy (MAE), and we find that in the case of Mn dimers,the exchange magnetic coupling is the dominant interaction, and thatthe ground state has the Mn spins in-plane with the GaN(000-1)substrate. In the Mn trimer case, the magnetic ground state also hasthe Mn spins in-plane with the GaN surface, but the relative spinorientation within each trimer is non-collinear. By exploring thenature of the magnetic interaction among the Mn trimers, we find thatthe surface states of the substrate play a key role, involving aRuderman-Kittel-Kasuya-Yosida (RKKY)-type interaction. To the best ofour knowledge, this is the first report of an electron-mediatedlong-distance exchange coupling between localized magnetic moments ona GaN(000-1) surface.p { margin-bottom: 0.25cm; line-height: 120% }