Quantum Materials - 01

Abstract

In the search for superconductors, measuring both electrical resistance and magnetization is essential, even under high pressure. We have developed devices using boron-doped diamond electrodes for resistance measurements under pressure [1], but magnetization measurements remain difficult due to limited sample size. Recently, nitrogen–vacancy (NV) centers in diamond have gained attention for quantum sensing under high pressure [2][3]. NV centers (spin s = 1) are sensitive to temperature, magnetic field, and pressure, enabling material property measurements. By integrating NV-diamond films with diamond anvils, simultaneous resistance and magnetization measurements under high pressure become possible.

In this study, we deposited NV-diamond films on diamond substrates using microwave plasma CVD and evaluated film quality by Raman and PL spectroscopy. First, to enable stable growth of high-crystallinity diamond, we optimized process parameters such as substrate temperature, microwave power, and gas ratios. Next, to control the NV concentration, nitrogen gas was introduced and its effect on NV incorporation was examined. Raman/PL spectra, obtained with a Renishaw inVia microscope using a 532 nm laser, provided information on crystallinity and defects. These results clarified relationships between growth parameters and film quality, laying the groundwork for high-pressure quantum sensing using NV-diamond films.