Vibronic effects on the quantum tunneling of magnetization in single-molecule magnets

Single-molecule magnets are among the most promising platforms for achieving molecular-scale data storage and processing at non-cryogenic temperatures [1]. Their magnetization dynamics are determined by an interplay between electronic and vibrational degrees of freedom, which can couple coherently leading to complex vibronic dynamics. While the relevance of the spin-phonon coupling for high-temperature magnetization dynamics is now well understood in terms of classical rate processes, its role in the low-temperature quantum tunneling regime is still debated and typically investigated with simplified models [2]. Here, we present a complete ab initio characterization of the magnetization dynamics of a dysprosocenium complex embedded in a realistic environment. Using a combination of perturbation theory and exact techniques, we quantify the contribution of vibronic interactions to the tunneling gap, and determine the conditions where vibronic contributions dominate. Our approach shows a direct connection between vibrational properties and quantum tunneling rates, and hence can point towards design guidelines for extending the fundamental limits to information storage in single-molecule magnets.

[1] C. Goodwin, F. Ortu, D. Reta et al., Nature 548, 439-442 (2017)

[2] K. Irländer, J. Schnack, Phys. Rev. B 102, 054407 (2020)