Impact of Finite Phonon Lifetimes on the Spin Dynamics of Single-Molecule Magnets

Abstract

The development of single-molecule magnets (SMMs) for information storage and processing relies on compounds with long spin lifetimes, and thus requires an understanding of the spin-phonon coupling. The phonon bath itself has a central role in these interactions, and hence knowledge of the impact of the intrinsic phonon lifetimes is crucial. Here we address this challenge by performing fully ab initio calculations of the phonon linewidths for a molecular crystal of a high-performance SMM. We find that the commonly assumed Born-Markov approximation is justified as phonon dynamics are orders of magnitude faster than the spin dynamics, and that employing ab initio-calculated linewidths in spin-dynamics simulations are secondary to employing a dense numerical sampling of the phonon modes in reciprocal space.

Investigating the Interplay Between Spin-Vibrational Coupling and Blocking Temperature in Designing High-Performance Pseudo D5h Dy(III) Single Ion Magnets

“…12 The Orbach process is a multiple one-phonon phenomenon where magnetization relaxation occurs by a sequential absorption of phonons involving excited mJ states and then sequential emission of phonons to reach the ground state by reversing its magnetization. [1][2][3][4][5][50][51][52] This Orbach relaxation becomes very slow at low temperatures due to the lack of thermally available phonons to initiate this process. 1-2, 4-5, 53 The Raman process is similar to Orbach, but it involves a virtual intermediate state of lattice and spin system which destroys the blocking barrier of magnetization reversal.…”