Bias-controlled ultrafast demagnetization in magnetic tunnel junctions

We report on the possibility of controlling the maximum demagnetization induced by a femtosecond laser pulse in a CoFeB-based magnetic tunnel junction, by tuning the external bias applied to the junction. We explain this effect in terms of laser-induced spin-polarized currents which can be controlled by tuning the conductivity of the junction. This demonstrates the contribution of spin- polarized currents for laser-induced demagnetization and may pave the way to increase the speed of spintronic devices, using ultrashort laser pulses.