Environmental effects on quantum relaxation and coherent dynamics in rare-earths ions

Abstract

This work provides new developments of the field of spin dynamics in mesoscopic systems. We first discuss, by a few examples, how environmental degrees of freedom affect tunneling and subsequent slow quantum relaxation of large molecule spins (such as Mn 12-AC) or rare-earth (RE) spins (such as Ho diluted in YLiF 4) showing two different facets of the spin bath model. The case of low molecule spins (V 15) is also considered. Then we discuss AC-susceptibility experiments performed on YLiF 4:Ho 3+ allowing to clarify the roles played by the phonon and the spin baths on single-ion and two-ion electro-nuclear tunneling. In the last part, we extend these quantum dynamical studies to the case of Er diluted in CaWO 4 where the spin and phonon baths are weak enough to allow fast and coherent quantum dynamics with the observation of Rabi oscillations. The angular momentum and magnetic moment of Er, J=15/2and 9 μ B, are comparable to those of large molecule spins, implying easy manipulations of potential RE solid-state qubits. © 2006 Elsevier B.V. All rights reserved.