Spin Hall Effect Detected at Room Temperature

PhysicsWeb is reporting that the spin Hall effect has been detected for the first time at room temperature. In the standard Hall effect, a voltage develops perpendicular to the current due to the influence of a magnetic field (see Lorentz Force). However, in the spin Hall effect, instead of a charge separation (as evidenced by the voltage) you get a spin separation. Electrons of one spin migrate to one side of the sample, while electrons of the opposite spin migrate to the opposite side. This effect will be important in "the growing field of spintronics, in which the intrinsic spin of the electron (in addition to its electrical charge) is exploited in the development of logic devices." Specifically, the spin Hall effect generates spin polarized currents, which can then be introduced into semi-conductor devices, where the "electrons could carry information based on the state (up or down) of their spin polarization."

"The spin Hall effect was first observed in GaAs at 20K by Awschalom and Yuichiro Kato in 2004 ... in a non-magnetic material and in the absence of an applied magnetic field." The most recent observations were made at temperatures from 10K to 295K in thin films of the material ZnSe. The effect was stronger at lower temperatures than at higher temperatures, resulting in the spin polarization (degree of separation) being about 20 times higher at 20K than at room temperature. Since it has been demonstrated that it is possible to produce this effect at room temperature, however, it is only a matter of time until the effect is made strong enough to use commercially.

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