Ultrafast quantum spin-state switching in the Co-octaethylporphyrin molecular magnet with a terahertz pulsed magnetic field

摘要

Molecular spin crossover switches are the objects of intense theoretical andexperimental studies in recent years. This interest is due to the fact thatthese systems allow one to control their spin state by applying an externalphoto-, thermo-, piezo-, or magnetic stimuli. The greatest amount of researchis currently devoted to the study the effect of the photoexcitation on thebi-stable states of spin crossover single molecular magnets (SMMs). The mainlimitation of photo-induced bi-stable states is their short lifetime. In thispaper we present the results of a study of the spin dynamics of the CoOEPmolecule in the Low Spin (LS) state and the High Spin (HS) state induced byapplying the magnetic pulse of 36.8 T. We show that the spin switching in caseof the HS state of the CoOEP molecule is characterized by a long lifetime andis dependent on the magnitude and duration of the applied field. Thus, afterapplying an external stimuli the system in the LS state after the spinswitching reverts to its ground state, whereas the system in the HS stateremains in the excited state for a long time. We found that the temperaturedependency of magnetic susceptibility shows an abrupt thermal spin transitionbetween two spin states at 40K. The proposed here theoretical approach opensthe way to create modern devices for spintronics with the controllable spinswitching process.