Influence of magnetic field orientation on laser-induced magnetization precession in Ni-Mn-Sn Heusler alloy film

Abstract

Laser-induced magnetization precession is investigated in Ni-Mn-Sn Heulser alloy film using pump-probe all-optical technique. The studies are performed as a function of external magnetic field H applied at various angles θH with respect to the sample normal. Strong dependence of precession parameters, frequency f, amplitude A and effective damping αeff on H and θH was found. For H>3 kOe and θH<25°, two precession modes, identified as Damon-Eshbach (DE) and first-order standing spin wave (PSSW) modes were observed. The values of wave vector k=0.37 μm−1 for DE mode and exchange constant Aex=0.22 μerg cm−1 for PSSW mode have been determined. The A(H) increases up to six times as θH decreases from 55° to 5° and exhibits a maximum at around H=1.8 kOe for each θH. From experimentally obtained exponentially decayed αeffH dependencies, intrinsic damping α0θH is estimated to ≈0.025. The dependencies of the magnetization precession parameters have been well simulated in the frame of phenomenological approach, based on Landau-Lifshitz-Gilbert equation.