Spin Berry points as crucial for ultrafast demagnetization

Laser-induced ultrafast demagnetization has puzzled researchers around the world for over two decades. Intrinsic complexity in electronic, magnetic, and phononic subsystems is difficult to understand microscopically. So far it not possible explain using a single mechanism, which suggests crucial piece of information still missing. In this paper, we return fundamental aspect physics: spin its change within each band entire Brillouin zone. We employ fcc Ni as an example use extremely dense {\bf k} mesh map out changes every close Fermi level along all high symmetry lines. To our surprise, angular momentum at some special points abruptly from $\pm \hbar/2$ $\mp simply by moving one crystal point next. This explains why intraband transitions, superdiffusion model based upon, can induce sharp moment reduction, electric current orientation spintronics. These points, are called Berry random appear when several bands other, so potential majority states different that minority states. Although band, jump, group neighboring together, they form distinctive smooth It structure disrupts those Spin laser-induced