Multimodal Quantum Sensing Platform for Ultrathin Spintronic Materials and Devices

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Advancement in magnetic sensor technologies is intimately intertwined with progress in magnetic materials and devices. Currently, the vast sensor toolkit for characterizing bulk magnetic materials is increasingly insensitive to nano-spintronic devices and recently-emerged atomically thin magnets, whose signals are too weak to be measured by conventional instruments. This project will demonstrate a unique nanoscale magnetometer with intrinsic quantum mechanical operation to address this timely challenge. This so-called “quantum sensor” is based on an isolated defect in the diamond lattice, known as the nitrogen-vacancy center in diamond. The goal is to develop novel technique and hardware systems to incorporate these sensors into an instrument for characterizing both the static and dynamic magnetic properties of ultrathin magnetic materials. The enabled measurement modes will be used to elucidate the nature of the magnetic phase transition and the interactions between magnetic atoms in novel materials, catalyzing progress towards higher performance magnetic devices. In addition, the project will develop a remotely accessible interface and educational resources for K-12 classrooms to explore manipulation of single quantum states. This hands-on exposure to quantum science for young students is expected to nurture the eventual participation of diverse groups in careers in science and engineering.Increasingly, conventional probes of bulk magnetism, such as commercial magnetometers based on the superconducting quantum interference device, are unable to detect the minuscule signals from atomically thin magnets and nano-spintronic devices. In recent years, the nitrogen-vacancy center in diamond has emerged as a superlative magnetometer capable of nanoscale proximity to ultrathin material samples, crucial for detecting the rapidly decaying dipolar fields from sample magnetizations. This project aims to establish a platform technology based on nitrogen-vacancy centers for the non-invasive probing of multi-modal magnetic properties, beyond static magnetization, and of diverse magnetic materials, beyond ferromagnets. The platform will demonstrate detection of dynamical magnetic fields created by both active material excitation and thermodynamic fluctuations, as well as develop modules for ac susceptibility and spin resonance in ultrathin samples. Advanced quantum control sequences will extend the coherence time of quantum sensors to achieve sensitivity surpassing commercial instruments. The unique capabilities developed here are expected to address open questions in ferromagnetism and antiferromagnetism in the two-dimensional limit and guide the development of next-generation magnetic memory, spin-based transistors, and ultrathin microwave components.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.