Microscopic Theory of Electron Spin Relaxation in N@ C60

Abstract

Endohedral N@C60 exhibits an extremely long electron spin relaxation time and offers a great potential in storing and processing quantum information. Here, we present a microscopic theory of electron spin relaxation in N@C60. The theory combines (1) the spin-orbit interaction of N 2p electrons, which mixes the ground-state 4S with excited 2P and 2D states, and (2) the coupling between the N 2p electrons and C60 Hg vibrations, which facilitates transitions between 2P and 2D states. The spin relaxation occurs via a two-phonon (Raman) process by absorbing a Hg phonon and emitting another at the (approximately) same frequency. The theory consistently explains measured spin relaxation time T1 and its temperature dependence, and predicts two independent spin decoherence T2 constants for ±3/2→±1/2 transitions.