The Spin Hall Effect (SHE) and related transport phenomena originating from the coupling of the charge and spin currents due to spin-orbit interaction were predicted 1. Following the suggestion in 2, the first experiments in this domain were done at Ioffe Institute in St. Petersburg 3, providing the first observation of what is now called the Inverse Spin Hall Effect. As to the SHE itself, it had to wait for 33 years before it was observed by two groups 4. The phenomenon consists in spin accumulation at the lateral boundaries of a current-carrying non-magnetic conductor, the spin directions being opposite at the opposing boundaries. The boundary spin polarization is proportional to the current and changes sign when the direction of the current is reversed. It exists in relatively wide spin layers determined by the spin diffusion length, typically on the order of 1μm. I will discuss the phenomenology of spin-charge coupling 5, the underlying microscopic mechanisms, and the existing experimental results obtained in semiconductors and in metals at cryogenic, as well as at room temperatures. I will also address the recently proposed 6 related phenomenon, the transformation (swapping) of spin currents, in which the spin direction and the direction of flow are interchanged. This is due to the correlation between spin rotation during a scattering event and the direction of scattering.
1. M.I. Dyakonov and V.I. Perel, JETP Lett. 13, 467 (1971); 2. N.S. Averkiev and M.I. Dyakonov, JETP Lett. 35, 196 (1983); 3. A.A. Bakun et al., JETP Lett. 40, 1293 (1984); 4. Y.K. Kato et al, Science, 306, 1910 (2004); J. Wunderlich et al, Phys. Rev. Lett. 94, 047204 (2005); 5. M.I. Dyakonov, Phys. Rev. Lett. 99, 126601 (2007); 6. M.B. Lifshits and M.I. Dyakonov, Phys. Rev. Lett. 103, 186601 (2009)
About Michel Dyakonov: Professor Dyakonov is a recipient of the State prize (USSR) in physics for theoretical work on spin dynamics (1976), the Frenkel prize of the St. Petersburg Physical Society, for theory of streamer discharge (1992) the Ioffe prize of the Russian Academy of Sciences for the theory of hot luminescence (1993), Beller Lectureship Award from the American Physical Society (2009) and the Grand prize from the French Physical Society (2009). He has his name attached to several physical phenomena: Dyakonov-Perel mechanism of spin relaxation in semiconductors, Dyakonov-Shur instability for plasma wave generation in 2D electron gas, Dyakonov waves at the interface of anisotropic media and the prediction (with V.I. Perel) of the Spin Hall Effect, confirmed in numerous experiments.