# Sensing Single-Molecule Magnets with Nitrogen-Vacancy Centers

## TL;DR

This paper uses diamond sensors to detect magnetic noise from single-molecule magnets at room and low temperatures, offering a new way to study their properties.

## Contribution

A novel method using nitrogen-vacancy centers to characterize single-molecule magnets at the nanoscale under realistic conditions.

## Key findings

- SMMs significantly influence the relaxation and decoherence times of NV centers.
- The magnetic noise spectral density of SMMs was inferred from NV measurements.
- Applied magnetic fields affect SMMs' noise spectral density at low temperatures.

## 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 surfaces and at room temperature remains challenging and requires
specialized nanoscale techniques. Here, we use single nitrogen-vacancy
(NV) centers in diamond as a highly sensitive, broadband magnetic
field sensor to detect the magnetic noise of cobalt-based SMMs deposited
on a diamond surface. We measured 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 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.