Dynamical response of nanoscale magnet in the environment with noise Original Research Article

We have investigated the effect of noise on the energy gap of the quantum resonant tunneling. By the use of the Landau–Zener–Stückelberg formula, we estimate the tunneling gap of the two level system with S=1/2 and also that of the lowest two levels in the realistic model with S=10. As observed in the corresponding experiments, the estimated gap has no velocity dependence in fast sweeping field in both systems. We show that a correction for the estimated energy gap is necessary for the two level system with S=1/2, while the effect of noise is negligible for the system with S=10. We discuss the difference between both systems and also interpretation of the experimental data.