Megabar pressure sensing and magnetic phase imaging by [111]-oriented nitrogen-vacancy centers in diamond

Abstract

High-precision pressure-magnetic field dual-mode detection under megabar pressures is achieved through a nitrogen vacancy (NV) quantum sensor integrated on a (111)-oriented diamond anvil culet. Experimental measurements reveal a linear pressure dependence of the NV center's zero-field splitting parameter D, demonstrating a characteristic slope of 7.94(4) MHz/GPa. This fundamental relationship enables the development of nonhydrostatic pressure sensing technology capable of operation up to 140 GPa without requiring traditional pressure-calibration media. In situ ferromagnetic/paramagnetic phase transition experiments on iron demonstrate the NV sensor's capability for submicrometer-scale pressure distribution imaging (spatial resolution of ∼500 nm) and magnetic field detection. Visualization of magnetic phase transition boundaries induced by pressure gradients confirms the sensor's ability to probe submicrometer-scale magnetism under extreme conditions. This method breaks through the limitations of traditional pressure gauges in nonhydrostatic conditions and provides a universal tool with high sensitivity and spatial resolution for research on high-pressure superconductivity, magnetic phase transitions, and quantum materials.