Illustration from Scientific Research

Examples of mirror-preserving (top) and mirror-broken (bottom) configurations. In a system that preserves time reversal, a charge with its spin at a certain positive momentum, under the action of such symmetries, goes into a charge with opposite spin (directed in the same direction but opposite in sign) at negative (symmetry related) momentum. For mirror-symmetric configurations, the sign change occurs when the spin lies in the mirror plane, as shown here. Instead, with currents included, strong asymmetry in their product L S occurs.

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