Revealing Condensed Matter Phenomena with Quantum Sensing

The single electron spin of a defect in diamond known as the nitrogen-vacancy (NV) center has emerged as a versatile nanoscale sensor for electromagnetic fields, temperature, and pressure, capable of operation in extreme environments and at diverse interfaces. In this talk, I will highlight our group’s efforts to extend the scope of NV quantum sensing to new materials science phenomena, such as dynamical magnetization responses and photocurrent, particularly for atomically thin materials, for which such measurements are inaccessible by conventional probes. We demonstrate the quantitative detection of the ac magnetic susceptibility and optically-induced, transient magnetization dynamics for few-layer van der Waals magnets [1,2]. Moreover, we image the vector photocurrent flow density and discover a hidden mechanism called the anisotropic photothermoelectric effect for photocurrent generation in the type-II Weyl semimetals WTe2 and TaIrTe4 [3]. Finally, we exploit nanoscale-resolved imaging to elucidate exchange bias and control over antiferromagnetic domains through antiferromagnetic-ferromagnetic interfaces at intrinsic layer-parity junctions in a 2D magnet. These quantum-enabled perspectives stimulate the unique understanding of quantum materials and new device archetypes for energy and information technologies.

1.    X.-Y. Zhang et al. ac susceptometry of 2D van der Waals magnets enabled by the coherent control of quantum sensors. PRX Quantum 2, 030352 (2021).
2.    X.-Y. Zhang et al. Enhanced magnetization by defect-assisted exciton recombination in atomically thin CrCl3. Physical Review Materials (2024).
3.    Y.-X. Wang et al. Visualization of bulk and edge photocurrent flow in anisotropic Weyl semimetals. Nature Physics (2023).