Effect of Thermal Fluctuation Field on the Magnetization Switching by Spin-Transfer Torque

In this work, the effect of thermal fluctuation field on the magnetization dynamics in Co1.5Fe1.5Ge alloy free layer is reviewed in a spin-valve structure with in-plane magnetization using the stochastic Landau-Lifshitz-Gilbert-Slonczewski (s-LLGS) equation taking into account the thermally assisted switching. The ultimate goal is to systematically study the heating effect on the magnetization reversal by simulating the magnetization dynamics in different thicknesses under very low current densities of about 106–105 A/cm2 in the presence of the thermal effect by applying different temperature values between T = 50 and T = 200 K. Results showed that the magnetization has different reversal processes among the large and small temperature values due to the competition between the thermal energy Et and magnetic energy barrier Eb, which allows the magnetization to trigger switching for specific temperature values. Consequently, at a temperature increase of about 200 K, we have proved that the magnetization reversal in Co1.5Fe1.5Ge alloy free layer is possible under a low current density of J =− 3.5 × 106 A/cm2. Additionally, we carefully examined the thermal impact on the threshold current density and switching time through analyzing the magnetization behavior for each temperature value, and as a result, we succeeded to reduce the critical current density in Co1.5Fe1.5Ge/Ag/Co1.5Fe1.5Ge structure from Jc = − 5.7 × 106 A/cm2 to Jc = − 9.5 × 105 A/cm2 for a thickness of 1 nm.