First-principles linear response theory for open quantum systems and its application to Orbach relaxation and direct magnetic relaxation in Ln -based coordination polymers
Year: 2026
Type: article
Abstract: Single-molecule magnets (SMMs) exhibit slow magnetic relaxation as a result of axial magnetic anisotropy inhibiting spin-phonon transitions. To establish a direct link between physical observables and the microscopic theory of magnetic relaxation, we here develop and numerically implement a first-principles linear response theory for open quantum systems that provides access to the complex alternating-current (ac) magnetic susceptibility in the presence of an oscillating ac magnetic field. Once combined with density functional theory and multiconfigurational electronic structure simulations, this formalism is applied in a fully first-principles fashion to three cyanido-bridged Ln /Y-based ( Ln = lanthanide) coordination polymers with general formula { Ln x III Y 1 − x III [ Co III ( CN ) 6 ] } , where Ln = Yb (), Tb (), and Dy (). The method is able to reproduce the low-temperature direct relaxation process and its field dependence, as well as the high-temperature Orbach relaxation regime for all the investigated compounds. These results demonstrate the feasibility of simulations of magnetic ac susceptibility in lanthanide-based SMMs and support the potential of further development of open quantum systems methods toward the completion of a magnetization dynamics theory.
DOI: 10.1103/f744-f6bq
Institution: Jagiellonian University
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7204272975