Extending the spin excitation lifetime of a magnetic molecule on a proximitized superconductor

TL;DR

This study demonstrates that a proximity-induced superconducting gold film can significantly extend the spin excitation lifetime of a magnetic molecule, enabling potential applications in quantum information processing.

Contribution

It shows that superconducting proximity effects in gold films can protect molecular spin excitations, achieving lifetimes over 80ns, which is a novel approach for spin preservation.

Findings

Spin excitation lifetime exceeds 80ns on proximitized gold.

Lifetime decreases with increasing film thickness.

Presence of de Gennes-Saint James resonances correlates with lifetime reduction.

Abstract

Magnetic molecules deposited on surfaces are a promising platform to individually address and manipulate spins. Long spin excitation lifetimes are necessary to utilize them in quantum information processing and data storage. Normally, coupling of the molecular spin with the conduction electrons of metallic surfaces causes fast relaxation of spin excitations into the ground state. However, the presence of superconducting paring effects in the substrate can protect the excited spin from decaying. In this work, we show that a proximity-induced superconducting gold film can sustain spin excitations of a FeTPP-Cl molecule for more than 80ns. This long value was determined by studying inelastic spin excitations of the S=5/2 multiplet of FeTPP-Cl on Au films over V(100) using scanning tunneling spectroscopy. The spin lifetime decreases with increasing film thickness, in apparent connection with the gradual gap-closing of a pair of de Gennes-Saint James resonances found inside the superconducting gap. Our results elucidate the use of proximitized gold electrodes for addressing quantum spins on surfaces, envisioning new routes for tuning the value of their spin lifetime.