Magnetic criticality-enhanced hybrid nanodiamond-thermometer under ambient conditions

TL;DR

This paper introduces a hybrid nano-thermometer combining NV centers and magnetic nanoparticles, achieving high temperature sensitivity near room temperature, enabling nanometer-scale thermal measurements in various scientific fields.

Contribution

The study demonstrates a novel hybrid nano-thermometer with enhanced temperature sensitivity using magnetic criticality, surpassing previous NV-based sensors under ambient conditions.

Findings

Temperature susceptibility of NV centers increased 100-fold near magnetic transition.

Achieved a temperature sensitivity of 11 mK/Hz^{1/2} at room temperature.

Monitored 0.3°C temperature variations with 60 ms resolution.

Abstract

Nitrogen vacancy (NV) centres in diamond are attractive as quantum sensors owing to their superb coherence under ambient conditions. However, the NV centre spin resonances are relatively insensitive to some important parameters such as temperature. Here we design and experimentally demonstrate a hybrid nano-thermometer composed of NV centres and a magnetic nanoparticle (MNP), in which the temperature sensitivity is enhanced by the critical magnetization of the MNP near the ferromagnetic-paramagnetic transition temperature. The temperature susceptibility of the NV center spin resonance reached 14 MHz/K, enhanced from the value without the MNP by two orders of magnitude. The sensitivity of a hybrid nano-thermometer composed of a Cu_{1-x}Ni_{x} MNP and a nanodiamond was measured to be 11 mK/Hz^{1/2} under ambient conditions. With such high-sensitivity, we monitored nanometer-scale temperature variation of 0.3 degree with a time resolution of 60 msec. This hybrid nano-thermometer provides a novel approach to studying a broad range of thermal processes at nanoscales such as nano-plasmonics, sub-cellular heat-stimulated processes, thermodynamics of nanostructures, and thermal remanent magnetization of nanoparticles.