Microscopic theory of spin-relaxation of a single Fe adatom coupled to substrate vibrations

TL;DR

This paper develops a parameter-free microscopic theory combining ab-initio electronic and vibrational properties to explain and predict spin-relaxation times of single Fe adatoms on substrates, aligning with recent experimental data.

Contribution

It introduces a novel, parameter-free theoretical framework that accurately models spin-relaxation in single adatoms by integrating electronic, vibrational, and many-body effects.

Findings

Reproduces millisecond spin lifetime measurements on Fe adatoms.

Shows how substrate decoupling layers and magnetic fields affect spin stability.

Proposes experimental signatures for localized spin-phonon excitations.

Abstract

Understanding the spin-relaxation mechanism of single adatoms is an essential step towards creating atomic magnetic memory bits or even qubits. Here we present an essentially parameter-free theory by combining \textit{ab-initio} electronic and vibrational properties with the many-body nature of atomic states. Our calculations account for the millisecond spin lifetime measured recently on Fe adatoms on MgO/Ag(100) and reproduce the dependence on the number of decoupling layers and the external magnetic field. We show how the atomic interaction with the environment should be tuned in order to enhance the magnetic stability, and propose a clear fingerprint for experimentally detecting a localized spin-phonon excitation.