Spin-orbit coupling induced strong magnetic anisotropy in actinide silicide (AnSi, An = Th, U, Np, Pu)

Magnetic anisotropy was a key property in magnetic storage and spintronic applications. In this work, we systematically investigate the magnetic anisotropy of actinide silicides AnSi (An = Th, U, Np, Pu) using first-principles calculations. The magnetic ground state, lattice stability, electronic structures, and isotropic exchange coupling based on the Heisenberg-Dirac spin-exchange Hamiltonian were analyzed in details. Spin-orbit coupling was found to play decisive role in determining the magnetic ground state, leading to tilted magnetic moment and non-collinear magnetism in these compounds. In particular, PuSi exhibited strong 5f spin polarization and intense ferromagnetic exchange interactions, resulting in a remarkably large magnetic anisotropy energy (MAE) of 64.51 meV with the easy axis along the z-direction. This high MAE highlights PuSi as a promising candidate for magnetic anisotropic materials. Our results elucidated the microscopic origin of magnetic anisotropy in 5f systems and provided valuable insights for actinide-based materials.