Ultrafast switching to zero field topological spin textures in ferrimagnetic TbFeCo films.

The capability of femtosecond (fs) laser pulses to manipulate topological spin textures on a very short time scale is sparking considerable interest. This article presents the creation of high density zero field topological spin textures by fs laser excitation in ferrimagnetic TbFeCo amorphous films. The topological spin textures are demonstrated to emerge under fs laser pulse excitation through a unique ultrafast nucleation mechanism, rather than thermal effects. Notably, large intrinsic uniaxial anisotropy could substitute the external magnetic field for the creation and stabilization of topological spin textures, which is further verified by the corresponding micromagnetic simulation. The ultrafast switching between topological trivial and nontrivial magnetic states is realized at an optimum magnitude of magnetic field and laser fluence. Our results would broaden the options to generate zero-field topological spin textures from versatile magnetic states and provides a new perspective for ultrafast switching of 0/1 magnetic states in spintronic devices.