najoNanosystems: Physics, Chemistry, MathematicsНаносистемы: физика, химия, математика2220-80542305-7971Университет ИТМО10.17586/2220-8054-2017-8-4-454-461najo-641Research ArticlePHYSICSФИЗИКАCalculations of the onset temperature for tunneling in multispin systemsCalculations of the onset temperature for tunneling in multispin systemsVlasovS. M.VlasovS. M.

Science Institute and Faculty of Physical Sciences

197101; Kronverkskiy, 49; St. Petersburg; 107 Reykjav´ık; Исландия

Science Institute and Faculty of Physical Sciences

197101; Kronverkskiy, 49; St. Petersburg; 107 Reykjav´ık; Iceland

BessarabP. F.BessarabP. F.

Science Institute and Faculty of Physical Sciences

197101; Kronverkskiy, 49; St. Petersburg; ; 107 Reykjav´ık; Исландия

Science Institute and Faculty of Physical Sciences

197101; Kronverkskiy, 49; St. Petersburg; 107 Reykjav´ık; Iceland

UzdinV. M.UzdinV. M.

197101; Kronverkskiy, 49; 198504; St. Petersburg

197101; Kronverkskiy, 49; 198504; St. Petersburg

v.uzdin@mail.ruJ´onssonH.J´onssonH.

Science Institute and Faculty of Physical Sciences; Department of Applied Physics

107 Reykjav´ık; Исландия; FIN-00076; Espoo; Финляндия

Science Institute and Faculty of Physical Sciences; Department of Applied Physics

107 Reykjav´ık; Iceland; FIN-00076; Espoo; Finland

ITMO University; Univ. of IcelandITMO University; Univ. of IcelandITMO University; St. Petersburg State UniversityITMO University; St. Petersburg State UniversityUniv. of Iceland; Aalto University;Univ. of Iceland; Aalto University20171308202584454461Copyright © Vlasov S.M., Bessarab P.F., Uzdin V.M., J´onsson H., 20252025Vlasov S.M., Bessarab P.F., Uzdin V.M., J´onsson H.Vlasov S.M., Bessarab P.F., Uzdin V.M., J´onsson H.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/641

   Transitions between magnetic states of a system coupled to a heat bath can occur by exceeding the energy barrier, but as temperature is lowered quantum mechanical tunneling through the barrier becomes the dominant transition mechanism. A method is presented for estimating the onset temperature for tunneling in a system with an arbitrary number of spins using the second derivatives of the energy with respect to the orientation of the magnetic vectors at the first order saddle point on the energy surface characterizing the over-the-barrier mechanism. An application to a monomer and a dimer of molecular magnets containing a Mn4 group is presented and the result found to be in excellent agreement with reported experimental measurements.

   Transitions between magnetic states of a system coupled to a heat bath can occur by exceeding the energy barrier, but as temperature is lowered quantum mechanical tunneling through the barrier becomes the dominant transition mechanism. A method is presented for estimating the onset temperature for tunneling in a system with an arbitrary number of spins using the second derivatives of the energy with respect to the orientation of the magnetic vectors at the first order saddle point on the energy surface characterizing the over-the-barrier mechanism. An application to a monomer and a dimer of molecular magnets containing a Mn4 group is presented and the result found to be in excellent agreement with reported experimental measurements.

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