Enhanced spin tunneling in a molecular magnet mixed with a superconductor

TL;DR

This study demonstrates that mixing Mn12 acetate magnetic ribbons with YBaCuO superconductor particles results in extremely narrow spin-tunneling resonances, due to magnetic field screening by superconducting Josephson currents.

Contribution

It reveals a novel method to enhance spin tunneling coherence in molecular magnets through superconductor-magnetic material interactions.

Findings

Narrow zero-field spin-tunneling resonance observed

Screening of internal magnetic fields by Josephson currents

Absence of inhomogeneous dipolar broadening

Abstract

We report characterization and magnetic studies of mixtures of micrometer-size ribbons of Mn$_{12}$ acetate and micrometer-size particles of YBaCuO superconductor. Extremely narrow zero-field spin-tunneling resonance has been observed in the mixtures, pointing to the absence of the inhomogeneous dipolar broadening. It is attributed to the screening of the internal magnetic fields in the magnetic particles by Josephson currents between superconducting grains surrounding the particles.