Standing spin waves in finite quantum spin spiral chains

Abstract

Standing spin waves in quantum spin-spiral chains are investigated using the local Pn and total absorbed power P. This method allows the investigation of the spin wave pattern and dispersion even if the quantum mechanical spin system initially has no magnetic order due to quantum fluctuations. In addition, the spin dynamics during resonance were examined more closely. Without taking damping into account, a multi-spin Rabi oscillation can be observed. The Rabi Oscillation disappears when damping is taken into account. The cause of this behavior becomes apparent when looking at the spin wave excitation in the semi-classical description. In the semi-classical description, also a Rabi oscillation occurs, which will be prevented by damping. The cause of the semi-classical Rabi oscillation is to be found in the effective field, which periodically drives the spins out of the equilibrium position or brings them in. The damping creates a spin torque directed against the effective field’s spin torque which results in small spin oscillations around its equilibrium position.