The coupling between ferromagnetism and electrical current has recently been the object of intense study because of the combination of interesting scientific developments and the potential technological impact. This coupling is mediated by spin current, the transport of electron spin that accompanies transport of electron charge in ferromagnetic metals. In one manifestation of ferromagnet-current coupling, called spin-transfer torque, the electrical current, acting through the spin current, can be used to move the domain pattern of the magnetization. The simplest description of this spin transfer torque anchors the magnetization in a medium that moves with the electron flow, such that magnetic features such as domain walls are carried "down-stream." In this issue, Vlaminck and Bailleu use a novel version of the Doppler effect to measure quantitatively the flow of this effective medium in a ferromagnetic wire.
Pub Type: Journals
Spin wave, Spin current, magnetic domain, domain wall, ferromagnetic resonance, Doppler effect, spin-transfer torque, giant magnetoresistance, MRAM, racetrack memory