Sensing single molecule magnets with nitrogen vacancy centers

TL;DR

This paper demonstrates the use of nitrogen-vacancy centers in diamond as sensitive sensors to detect and analyze the magnetic noise of single-molecule magnets at room and low temperatures, advancing nanoscale magnetic characterization.

Contribution

It introduces a novel method employing NV centers to characterize SMMs on surfaces at room temperature, enabling realistic condition analysis.

Findings

NV centers detect magnetic noise of SMMs at 296 K and 5-8 K.

SMMs influence NV relaxation and decoherence times.

Magnetic field affects SMMs' magnetic noise spectral density.

Abstract

Single-molecule magnets (SMMs) are molecules that can function as nanoscale magnets with potential use as magnetic memory bits. While SMMs can retain magnetization at low temperatures, characterizing them on surface and at room temperature remains challenging and requires specialized nanoscale techniques. Here, we use single nitrogen-vacancy (NV) centers in diamond as highly sensitive, broadband magnetic field sensors to detect the magnetic noise of cobalt-based SMMs deposited on a diamond surface. We measure the NV relaxation and decoherence times at 296 K and at 5-8 K, observing a significant influence of the SMMs on them. From this, we can infer the SMMs' magnetic noise spectral density (NSD) and underlying magnetic properties. Moreover, we observe the effect of an applied magnetic field on the SMMs' NSD at low temperatures. The method provides nanoscale sensitivity for characterizing SMMs under realistic conditions relevant to their use as surface-bound memory units.