Reviewed by Lexie CornerMar 6 2025
A team of researchers developed a new method for measuring high-speed fluctuations in magnetic materials at the nanoscale. The findings, published in Nano Letters, could aid in the development of technologies ranging from traditional computing to emerging quantum computing.
A single-spin qubit probes nanoscale spin fluctuations to reveal magnetic interactions in quantum materials. Image Credit: Andy Sproles/ORNL, US Department of Energy
Phase transitions in many materials are characterized by stepwise changes in key properties that depend on temperature. Understanding how materials behave near a critical transition temperature is crucial for developing new technologies that use these unique physical characteristics.
The team used a nanoscale quantum sensor in this study to measure spin fluctuations in a magnetic thin film near a phase transition. The ability to precisely control and manipulate the magnetic properties of room-temperature thin films is important for applications in electronic devices, sensors, and data storage.
The researchers used a scanning nitrogen-vacancy center microscope, a specialized tool at the Center for Nanophase Materials Sciences, a DOE Office of Science user facility at ORNL. A nitrogen-vacancy center is an atomic-scale defect in a diamond, where a nitrogen atom replaces a carbon atom and a nearby carbon atom is missing. This defect creates a unique configuration of quantum spin states, which responds to both static and fluctuating magnetic fields, enabling researchers to study nanoscale structures by detecting signals at the single-spin level.
The nitrogen-vacancy center functions as both a quantum bit, or qubit, and a highly sensitive sensor that we moved around on top of the thin film to measure temperature-dependent changes in magnetic properties and spin fluctuations that cannot be measured any other way.
Ben Lawrie, Research Scientist, Materials Science and Technology Division, Oak Ridge National Laboratory
When a material's magnetic properties are determined by its spin orientation, it continuously changes direction instead of remaining constant. This behavior is known as spin fluctuations. As the thin film underwent a phase transition between different magnetic states due to changes in temperature, the team recorded these spin fluctuations.
The measurements revealed the global relationship between local variations in spin fluctuations near phase transitions. This nanoscale insight into interacting spins could lead to a deeper understanding of various quantum materials and contribute to the development of new spin-based information processing technologies.
Advances in spintronics will improve digital storage and computing efficiency. Meanwhile, spin-based quantum computing offers the tantalizing promise of classically inaccessible simulation if we can learn to control interactions between spins and their environment.
Ben Lawrie, Research Scientist, Materials Science and Technology Division, Oak Ridge National Laboratory
This research connects ORNL’s expertise in quantum information and condensed matter physics.
If we can use today’s generation of quantum resources to gain new understanding of classical and quantum states in materials, that will help us to design new quantum devices with applications in networking, sensing, and computing.
Ben Lawrie, Research Scientist, Materials Science and Technology Division, Oak Ridge National Laboratory
The study was supported by the DOE Basic Energy Sciences program.
Journal Reference:
Wu, Y., et al. (2025) Nanoscale Magnetic Ordering Dynamics in a High Curie Temperature Ferromagnet. Nano Letters. doi/10.1021/acs.nanolett.4c05401?goto=supporting-info