X.-Y. Zhang, Y.-X. Wang, T. A. Tartaglia, T. Ding, M. J. Gray, K. S. Burch, F. Tafti, and B. B. Zhou. ac Susceptometry of 2D van der Waals Magnets Enabled by the Coherent Control of Quantum Sensors. PRX Quantum 2, 030352 (2021). Editors’ Suggestion.
Recently discovered 2D magnets have created tremendous excitement, but progress towards applications is hampered by the inability of commercial magnetometers to detect their minuscule magnetic moments. Now, we demonstrate that a quantum magnetometer based on single electron spins in diamond can serve as a multimodal (ac/dc) magnetic properties measurement system (MPMS) for atomically-thin magnets.
In this work, we develop a new technique to detect both dc (static) and ac (dynamic) fields produced by ultrathin magnetic materials. By coherently controlling the quantum evolution of the sensor, we tune the sensor response, like a radio, to the oscillating magnetic fields produced by a nanometer-thin, micron-wide magnet. These ac fields reveal the dynamical response of the ultrathin magnet to periodic excitation, highlighting the motion of domain walls and the rotation of the magnetic axis inside the material. This response, known as the magnet’s “ac susceptiblity”, is vitally important for dynamically-switchable magnetic technologies, including memory, logic, and transformers.
The developed sensing modality can be combined with other strengths of NV magnetometry, such as nanoscale imaging and operation in high pressure environments, to allow a multi-faceted understanding of new materials. It could lead to a second generation of quantum-coherent magnetometers for nanoscale materials that sit alongside existing instruments for bulk materials in national labs and universities worldwide.
We gratefully acknowledge NSF ENG (ECCS-2041779) for supporting our efforts toward a Quantum Diamond MPMS for ultrathin/ultrasmall materials.