Effect of uniaxial magnetic anisotropy on charge transport in a junction with a precessing anisotropic molecular spin

Anisotropic magnetic molecules can be employed to manipulate charge transport in molecular nanojunctions. Charge transport through a molecular orbital connected to two leads and exchange-coupled with a precessing anisotropic molecular spin in a constant magnetic field is studied here. The magnetic field and the uniaxial magnetic anisotropy parameter of the molecular spin modulate the total precession frequency. The precessing molecular magnetization drives inelastic tunneling processes between electronic quasienergy levels. The dc-bias voltages allow to unveil the quasienergy levels, Larmor frequency, and the anisotropy parameter, through characteristics of charge-transport measurements involving features such as steps, peaks, and dips. Quantum interference effects between states connected with spin-flip events are reflected in the shot noise as peak-dip (dip-peak) features, resembling Fano-like resonance profiles, and are controlled by the anisotropy parameter and Larmor frequency. Under zero bias, the increase of the anisotropy parameter enables the decrease of the precession frequency or alters the precession direction, and shot noise is reduced. Furthermore, it is possible to adjust the anisotropy parameter to suppress the precession frequency, leading to the suppression of shot noise. The results show that in the given setup, the charge current and shot noise can be controlled by the magnetic anisotropy parameter of the molecular spin.