A simplified representation of the new technology is shown. Two magnetic layers, each with a different magnetization, are separated by a neutral layer. A laser pulse strikes electrons in the upper layer. This causes them to move through the material, in the direction of the second layer. The spin of these electrons, in the direction of the magnetization of the upper layer, exerts a force on the spin of the electrons in the lower layer to make them rotate in the same direction. This makes the magnetization in the second layer change.