Magnetization reversal more rapidly by using an ultrashort square-wave laser

Abstract

With the feature of low-power and ultrashort time magnetization manipulation, all optical magnetic switching (AOMS) has been propelled to the forefront in investigations. To further speed up the magnetization reversal, in this paper, based on the combination of heating and Inverse Faraday Effect (IFE), an ultrashort square-wave laser (USWL) pulse is explored to excite the reversal of magnetization in a Co/Pt system, and all the parameters necessary for our simulation are well within the current theoretical estimates. Simulation results show that the switching time of magnetization is 3 times faster than the using of a traditional ultrashort Gaussian wave laser (UGWL) under the same laser fluence F = 4 mJ/cm2 and pulse duration t0 = 35 fs, and the threshold of AOMS for the ferromagnet is 0.67 mJ/cm2. We furthermore demonstrate that the heat accumulating effect of a laser-pulse is an important factor that influences the switching time, and a USWL has a larger effect of heat accumulating than a UGWL. At present, the debate on the origin of helicity dependent AOMS is still going on, and the model we propose provide a guideline for achieving helicity dependent AOMS more rapidly. We believe that the results could potentially be used to the field of storage technology especially for the using of AOMS.