najoNanosystems: Physics, Chemistry, MathematicsНаносистемы: физика, химия, математика2220-80542305-7971Университет ИТМО10.17586/222080542015615762najo-901Research ArticleCONTRIBUTED TALKSCONTRIBUTED TALKSThermally induced transitions and minimum energy paths for magnetic systemsAlexandrovE. V.

St. Petersburg

aloraman@live.comITMO UniversityRussian Federation201515082025615762Copyright © Alexandrov E.V., 20252025Alexandrov E.V.Alexandrov E.V.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://nanojournal.ifmo.ru/jour/article/view/901

Thermally induced magnetic transitions are rare events as compared with vibrations of individual magnetic moments. Timescales for these processes differ by 10 orders of magnitude or more. Therefore, the standard MonteCarlo simulation is not suitable for the theoretical description of such phenomena. However, a statistical approach based on transition state theory is applicable for calculations of the transition rates. It presupposes finding the minimum energy path (MEP) between stable magnetic states on the multidimensional energy surface of the system. A modification of the Nudged Elastic Band (NEB) method for finding the energy barriers between states is suggested. A barrier on the energy surface corresponds to the difference between maximum energy along the MEP (highest saddle point) and the initial state minimum. The NEB procedure is implemented for spin rotations in Cartesian representation with geometric constraint on the magnitude of the magnetic moment. In this case, the effective magnetic forces are restricted to the tangent plane of the magnetic momentum vector.

Potential energy surfaceminimum energy pathnudged elastic band methodnumerical optimizationquick minmodeThis work was partially supported by RFBR grant No. 140200102 and NordicRussian Training Network for Magnetic Nanotechnology (NCMRU10121). Helpful discussions with Pavel Bessarab, Valery Uzdin and Hannes J´onsson are gratelfully acknowledged.ReferencesLoth S., Baumann S., et al. Bistability in atomicscale antiferromagnets. Science, 335, P. 196–198 (2012).Loth S., Baumann S., et al. Bistability in atomicscale antiferromagnets. Science, 335, P. 196–198 (2012).Bessarab P.F., Uzdin V.M., J´onsson H. Harmonic transitionstate theory of thermal spin transitions. Phys. Rev. B, 85, P. 184409 (2012).Bessarab P.F., Uzdin V.M., J´onsson H. Harmonic transitionstate theory of thermal spin transitions. Phys. Rev. B, 85, P. 184409 (2012).J´onsson H., Mills G., Jacobsen K.W. Nudged elastic band method for finding minimum energy paths of transitions. Proceedings of the Conference ‘International School of Physics. Classical and quantum dynamics in condensed phase simulations’, Lerici, Italy, July 1997, P. 385–404 (1997).J´onsson H., Mills G., Jacobsen K.W. Nudged elastic band method for finding minimum energy paths of transitions. Proceedings of the Conference ‘International School of Physics. Classical and quantum dynamics in condensed phase simulations’, Lerici, Italy, July 1997, P. 385–404 (1997).Henkelman G., J´ohannesson G., J´onsson H. Methods for finding saddle points and minimum energy paths, in Progress on Theoretical Chemistry and Physics. Kluwer Academic Publishers, Dordrecht, the Netherlands, 2000, P. 269–300 (2000).Henkelman G., J´ohannesson G., J´onsson H. Methods for finding saddle points and minimum energy paths, in Progress on Theoretical Chemistry and Physics. Kluwer Academic Publishers, Dordrecht, the Netherlands, 2000, P. 269–300 (2000).Bessarab P.F., Uzdin V.M., J´onsson H. Potential energy surfaces and rates of spin transitions. Zeitschrift fur Physikalische Chemie, 227, P. 1543 (2013).Bessarab P.F., Uzdin V.M., J´onsson H. Potential energy surfaces and rates of spin transitions. Zeitschrift fur Physikalische Chemie, 227, P. 1543 (2013).Henkelman G., J´onsson H. Improved tangent estimate in the NEB method for finding minimum energy paths and saddle points. J. Chem. Phys., 113, P. 9978 (2000).Henkelman G., J´onsson H. Improved tangent estimate in the NEB method for finding minimum energy paths and saddle points. J. Chem. Phys., 113, P. 9978 (2000).Henkelman G., Uberuaga B., J´onsson H. A ClimbingImage NEB Method for finding saddle points and minimum energy paths. J. Chem. Phys., 113, P. 9901 (2000).Henkelman G., Uberuaga B., J´onsson H. A ClimbingImage NEB Method for finding saddle points and minimum energy paths. J. Chem. Phys., 113, P. 9901 (2000).

The authors declare that there are no conflicts of interest present.