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

TL;DR

This study demonstrates ultrafast, terahertz magnetic field-induced spin switching in a molecular magnet, revealing long-lived high-spin states and potential for spintronic device applications.

Contribution

It provides new insights into magnetic pulse-induced spin dynamics in CoOEP molecules, highlighting long-lived high-spin states and temperature-dependent spin transitions.

Findings

Spin switching depends on magnetic pulse magnitude and duration.

High-spin state remains long-lived after excitation.

Abrupt spin transition occurs at 40K.

Abstract

Molecular spin crossover switches are the objects of intense theoretical and experimental studies in recent years. This interest is due to the fact that these systems allow one to control their spin state by applying an external photo-, thermo-, piezo-, or magnetic stimuli. The greatest amount of research is currently devoted to the study the effect of the photoexcitation on the bi-stable states of spin crossover single molecular magnets (SMMs). The main limitation of photo-induced bi-stable states is their short lifetime. In this paper we present the results of a study of the spin dynamics of the CoOEP molecule in the Low Spin (LS) state and the High Spin (HS) state induced by applying the magnetic pulse of 36.8 T. We show that the spin switching in case of the HS state of the CoOEP molecule is characterized by a long lifetime and is dependent on the magnitude and duration of the applied field. Thus, after applying an external stimuli the system in the LS state after the spin switching reverts to its ground state, whereas the system in the HS state remains in the excited state for a long time. We found that the temperature dependency of magnetic susceptibility shows an abrupt thermal spin transition between two spin states at 40K. The proposed here theoretical approach opens the way to create modern devices for spintronics with the controllable spin switching process.