Applied Physics

Spinning into View

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Science  26 Mar 2010:
Vol. 327, Issue 5973, pp. 1555
DOI: 10.1126/science.327.5973.1555-b

The efficiency of electrical devices is compromised considerably by Joule heating. In an attempt to thwart this effect, spintronics seeks to manipulate the electron's spin rather than its charge. This manipulation is perhaps best exemplified by the spin-transfer torque effect, in which passing a spin current from one ferromagnetic layer into another through an intervening nonmagnetic film (the so-called magnetic tunnel junction) causes the relative polarization of the two ferromagnetic layers to switch from parallel to antiparallel, or vice versa. This switching process has been challenging to characterize on a single-shot basis as the signal (change in conductance) is quite weak. Now, in a single-event experiment, Cui et al. resolve not just the switch itself but the smaller oscillations of the conductance leading to a switch (reflecting the increasingly intense precession of the spins). As the measurements are performed at room temperature and thermal effects are important in assisting the switching process, the observed dynamics may be more generally applicable to nonlinear systems in warm environments.

Phys. Rev. Lett. 104, 97201 (2010).

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