Theory of Tunneling Assisted Electron Spin–Lattice Relaxation

Abstract

It is shown for an Eg orbital state and a tunneling splitting which is small compared with the Zeeman splitting that a strong Jahn–Teller coupling can lead to an enhancement of the direct spin–phonon coupling by several orders of magnitude. By comparing the theory with low temperature relaxation measurements on Cu2+ in a double nitrate the magnitude of several of the significant parameters associated with the Jahn–Teller problem is derived. A T2g orbital state strongly coupled to t2g modes of vibration can also have a strong spin–phonon coupling; the corresponding situation is briefly discussed.The strong coupling of the vibronic states to the lattice and the considerable range in the strength of this coupling have a number of practical applications.