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A new way to control electron spin

An international group of experimental and theoretical physicists has presented a new technique believed to be able to control a fundamental property of electrons—the upward or downward orientation of their spin—while these particles move inside a film of gallium arsenide, a wafer-thin two-dimensional semiconductor material  (Physical Review X, June 1, 2017). By applying different electrical voltages on the material, the researchers manipulated the balance between two effects (the Rashba and Dresselhaus effects) that generate opposing magnetic fields and are responsible for preserving the spin orientation of the moving electrons. “The fields may vary, but they are in synch, which locks the electron spin for a while,” explains theoretical physicist José Carlos Egues of the São Carlos Institute of Physics (IFSC) at the University of São Paulo (USP), a coauthor of the study. Depending on how much current is applied, the spin orientation is maintained for a longer or shorter time while the electron “travels” along the semiconductor material in a stretchy wave texture. Controlling electron spin, which tends to change position as the particles move, is an essential prerequisite for storing and recovering data on any quantum chip.