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A research team led by the Department of Energy’s Oak Ridge National Laboratory (ORNL) has introduced an innovative method for measuring rapid fluctuations in magnetic materials at nanoscale dimensions, equivalent to billionths of a meter. The findings, shared in the journal Nano Letters, hold the potential to drive advancements in a variety of technological sectors, including traditional and quantum computing.
Materials often experience phase transitions, where critical properties change in a temperature-dependent manner. Gaining insight into how materials behave near these critical transition points is essential for developing new technologies that exploit their unique physical characteristics. In this investigation, researchers utilized a nanoscale quantum sensor to observe spin fluctuations in a magnetic thin film as it approached a phase transition.
Thin films with magnetic properties at room temperature play a vital role in data storage capabilities, sensors, and electronic devices, due to the precise control they allow over magnetic features. The team employed a specialized tool known as a scanning nitrogen-vacancy center microscope located at the Center for Nanophase Materials Sciences, a user facility supported by the Department of Energy. This microscope features nitrogen-vacancy centers—atomic-scale defects in diamond formed when a nitrogen atom replaces a carbon atom, resulting in a unique configuration that allows for the detection of both static and fluctuating magnetic fields on a single spin level, thus facilitating the analysis of nanoscale structures.
Ben Lawrie, a research scientist in ORNL’s Materials Science and Technology Division, remarked, “The nitrogen-vacancy center serves dual purposes as both a qubit and a highly sensitive sensor, which we maneuvered over the thin film to track temperature-dependent deviations in magnetic properties and spin fluctuations that traditional methods cannot capture.”
The phenomenon of spin fluctuations occurs when the magnetic properties of a material, controlled by spin orientation, continuously change rather than maintain a steady direction. The researchers monitored these fluctuations as the thin film transitioned between various magnetic states due to temperature manipulation.
The data collected provided insights into how local spin fluctuation alterations are interlinked globally near phase transitions. This granular understanding of interacting spins is poised to foster the development of new technologies based on spin-based information processing, as well as advancements in our understanding of various quantum materials.
Lawrie emphasized the significance of spintronics, stating, “Enhancements in this field are set to boost the efficiency of digital storage and computing. Additionally, exploration of spin-based quantum computing holds the alluring potential for simulating phenomena that are currently beyond our classical computational capabilities, provided we learn to manage spin interactions effectively.”
This research exemplifies the intersection of ORNL’s focus on quantum information science and condensed matter physics. “Leveraging contemporary quantum resources to deepen our comprehension of classical and quantum states in materials could pave the way for designing innovative quantum devices applicable in networking, sensing, and computing,” Lawrie added.
The Department of Energy’s Basic Energy Sciences program sponsored this research effort.
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