Quantum Sensing Revolutionizes Magnetic Material Analysis for Next-Generation Power Electronics
The quest for greater energy efficiency is driving innovation in power electronics, with wide-bandgap semiconductors like gallium nitride (GaN) and silicon carbide (SiC) leading the charge. However, realizing the full potential of these advanced devices hinges on minimizing energy losses in passive components – a challenge directly tied to the properties of the soft magnetic materials used within them. Now,a groundbreaking progress in quantum sensing is offering an unprecedented ability to analyze these materials,paving the way for significant advancements in efficiency and miniaturization.
Researchers at the institute of Science Tokyo, in collaboration with Harvard University and Hitachi, Ltd., have pioneered a novel imaging technique utilizing diamond quantum sensors to simultaneously map both the amplitude and phase of alternating current (AC) stray fields across a remarkably wide frequency range – up to 2.3 MHz. This breakthrough, recently published in Communications Materials, provides a powerful new tool for characterizing and optimizing soft magnetic materials crucial for high-frequency applications.
The Challenge of High-Frequency Losses
Traditional methods for analyzing magnetic losses often struggle at higher frequencies, hindering the development of materials capable of supporting the next generation of power electronics. Energy losses in these components manifest as heat, reducing efficiency and limiting the potential for smaller, more powerful devices. Understanding the underlying mechanisms of these losses – especially hysteresis and eddy current losses – is therefore paramount.
The key to unlocking this understanding lies in accurately characterizing the behavior of magnetic fields within the material itself. This is where the innovative approach of Professor Mutsuko Hatano’s team comes into play.
Diamond Quantum Sensors: A new Lens on Magnetism
The team leveraged the unique properties of diamond quantum sensors containing nitrogen-vacancy (NV) centers. These NV centers act as incredibly sensitive detectors of magnetic fields, offering nanoscale spatial resolution. However, simply detecting the magnetic field isn’t enough; understanding how the field changes over time - its phase – is equally critical for quantifying energy dissipation.
To achieve this, the researchers developed two distinct quantum protocols:
Qubit Frequency Tracking (Qurack): Optimized for frequencies in the kilohertz (kHz) range, Qurack precisely tracks changes in the qubit frequency induced by the AC magnetic field.
Quantum Heterodyne (Qdyne) Imaging: Designed for the megahertz (MHz) range, Qdyne utilizes a heterodyne detection scheme to resolve the phase of the AC magnetic field with high accuracy.
By combining these two protocols, the team created a system capable of wide-range AC magnetic field imaging, a capability previously unattainable. Validation experiments, involving imaging the AC magnetic field generated by a 50-turn coil, confirmed the accuracy and spatial resolution (2-5 µm) of both Qurack and Qdyne.
Unveiling Energy Loss Mechanisms in CoFeB-SiO2 Thin Films
To demonstrate the power of their technique, the researchers applied it to analyze CoFeB-SiO2 thin films – materials commonly used in high-frequency inductors. The results were revealing. They discovered that these films exhibited minimal phase delay (near-zero) up to 2.3 MHz when the magnetization was driven along the “hard axis” – the direction requiring the most energy to magnetize. This indicates exceptionally low energy losses in this configuration.
Though,when the magnetization was driven along the “easy axis” – the direction of natural magnetization – the phase delay increased significantly with frequency,signaling higher energy dissipation. This crucial finding highlights the strong dependence of energy loss on the material’s magnetic anisotropy.
Implications for Power Electronics and Beyond
This research represents a significant leap forward in the characterization of soft magnetic materials. The ability to simultaneously map amplitude and phase across a broad frequency range provides unprecedented insight into the complex mechanisms governing energy loss.
The implications extend far beyond power electronics. This technique holds promise for advancements in:
Electromagnets: Optimizing magnetic core materials for increased efficiency.
Non-Volatile Memory: Developing more energy-efficient data storage solutions.
* Spintronics: Exploring novel magnetic materials for advanced electronic devices.
Future Directions and the Quantum Horizon
Professor Hatano’s team is already looking towards further refinements of their techniques. Planned improvements include enhancing Qurack’s amplitude range through advanced signal generators and broadening Qdyne’s frequency detection range by optimizing spin coherence time and microwave control speed.
“Simultaneous imaging of the amplitude and phase of AC magnetic fields across a broad frequency range offers numerous potential applications,” Hatano explains. “This success contributes to the acceleration of quantum technologies, particularly in sectors related to lasting development goals and well-being.”
This work underscores the transformative potential of quantum sensing, not just as a scientific curiosity, but as a practical tool driving innovation in critical technologies and contributing to a more sustainable future. The ability to resolve domain wall motion – a key magnetization mechanism linked to
