Temperature Dependence of Rashba Spin-orbit Coupling in Quantum Wells

We perform an all-optical spin-dynamic measurement of the Rashba spin-orbit interaction in (110)-oriented GaAs/AlGaAs quantum wells. The crystallographic direction of quantum confinement allows us to disentangle the contributions to spin-orbit coupling from the structural inversion asymmetry (Rashba term) and the bulk inversion asymmetry. We observe an unexpected temperature dependence of the Rashba spin-orbit interaction strength that signifies the importance of the usually neglected higher-order terms of the Rashba coupling.