Spin texture
= Spin texture
{title2=$\mathbf s(\mathbf r)\text{ or }\mathbf s(\mathbf k)$}
A spin texture describes how a <spin expectation value> or <spin polarization> varies with <position> or <wavevector>. It specifies a <vector field>, including its magnitude when that matters; a direction field alone is undefined wherever that magnitude vanishes. A <Rashba spin texture> is an example in which <spin expectation values> wind around circles in the plane of <wavevectors>.