Abstract

The study of spin dynamics nowadays is very crucial for the implementation of magnetic memory based spintronic devices for future technologies. In this way, logical “1” and “0” can be associated with spin up and down states respectively and we can alter the states using THz laser pulse. Recent theoretical and experimental studies have shown that the magnetic field-derivative torque (FDT) plays an important role in influencing the spin dynamics including the spin switching mechanisms, in the THz regime.[1,2] In relation to this, the ferrimagnetic garnet Gd3/2Yb1/2BiFe5O12 reflects a very good signature of the effect of FDT.[3] In this presentation, I will discuss about the influence of FDT in the spin dynamics, particularly the spin switching dynamics of the mentioned garnet system. Starting from a Hamiltonian which includes exchange interaction, uniaxial anisotropy and Zeeman interaction, we find out the effective magnetic field acting on the system. We use Landau-Lifshitz-Gilbert (LLG) equation to delineate the temporal evolution of magnetization in the system computationally. Our results revealed that due to the effect of FDT, switching of spin requires lesser THz magnetic field than the one reported before.[4] It has come out that the effect of FDT is dependent upon specific material parameters like damping parameter, sublattice volume per spin and gyromagnetic ratios of individual sublattices in the magnetic system.[5]


References:
[1] R. Mondal et al., Phys. Rev. B 100, 090409 (2019)
[2] A. Dutta, … , S. Bhattacharjee et al., Phys. Rev. Mater. 8, 114404 (2024)
[3] A. Dutta et al., Adv. Funct. Mater. 35, 2414582 (2024)
[4] P. Mukherjee, … , S. Bhattacharjee et al., Phys. Rev. Mater. 9, 104405 (2025)
[5] S. Bhattacharjee, P. Mukherjee and R. Mondal, manuscript in preparation