Quantum switching by making use of adiabatic changes: Landau-Zener-Stuckelberg mechanism and Rosen-Zener mechanism

A mechanism of switching between states of different magnetizations without hysteresis loss is proposed in quantum magnets. We use quantum mechanical dynamics at the avoided level crossing structure. There, the Landau-Zener-Stuckelberg mechanism for the nonadiabatic transition plays an important role in changing quantum state. We demonstrate this mechanism in a Heisenberg spin model forming a dimer state, where the singlet and triplet states are switched to each other by applying a time-dependent external field. We also study the switching mechanism by rotating the direction of the field to control the gap due to the anisotropy of the Dzyaloshinskii-Moriya interaction.