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O: Fachverband Oberflächenphysik
O 37: Poster Session III: Surface magnetism III
O 37.7: Poster
Tuesday, March 2, 2021, 10:30–12:30, P
Local pairwise exchange interactions for noncollinear states in itinerant-electron magnets — •Kseniia Vodenkova1 and Pavel Bessarab1,2 — 1ITMO University, St. Petersburg, Russia — 2University of Icelad, Reykjavik, Iceland
The microscopic origin of the exchange interactions for noncollinear ordering of atomic magnetic moments in itinerant-electron systems is a subject of ongoing scientific discussions. In this work, we derive by means of the multiple-scattering theory a general expression for pairwise magnetic exchange interaction parameters for an arbitrary noncollinear, nonstationary magnetic state. In contrast to previous approaches, our formalism takes into account the variation of the fast degrees of freedom such as charge density and magnetic moment length. Application of the formalism to a tight-binding model reveals a range of magnetic systems that can be described by a classical Heisenberg Hamiltonian reasonably well. For other systems, our approach makes it possible to systematically derive atomistic spin Hamiltonians beyond the Heisenberg model. Moreover, the expression for the pairwise interaction tensor describes a local curvature of the energy surface of the system as a function of the orientation of magnetic vectors. This can be used in various contexts including description of thermal stability of magnetic states within the harmonic transition state theory and efficient identification of stable magnetic configurations using the Newton-Raphson method.
This work was funded by the Russian Science Foundation (Grant No.19-72-10138).