Physicists with the USC Dornsife College of Letters, Arts and Sciences, Cornell University and collaborating institutions have created a microscopic device that can both detect and control the rapid “dance” of electron spins in antiferromagnetic materials — a leap that could enable a new generation of ultrafast, energy-efficient electronics.
The work was published this month in Science.
- Antiferromagnetic materials are solids in which electrons spin in opposite directions, canceling each other’s This zero-magnetism makes them fast, stable and immune to outside magnetic interference.
- Until now, scientists could only detect this quantum behavior using bulky lab equipment — making it hard to imagine practical uses in everyday tech.
Why it matters: Antiferromagnets can operate at mind-boggling speeds — trillions of cycles per second — and could support real-world applications that include:
- Ultra-secure, lightning-fast wireless communications, well beyond 5G speeds.
- Ultra-high-resolution medical imaging.
- Safer airport security scanning without X-rays.
- Nano-oscillators that convert a static voltage to high-frequency signals, useful in a wide range of applications, including advanced computers and sensors.
And it does all of this with a device just a few atoms thick, using only electric signals — no room-sized equipment required.
The work was made possible by funding from the National Science Foundation and the U.S. Department of Energy — two key supporters of fundamental research driving tomorrow’s technology.
The breakthrough: The team built a microscopic structure called a “tunnel junction” made of three, ultra-thin stacked layers of materials. This tiny device can do two key things:
- Detect antiferromagnetic resonance — the natural vibration of opposing electron spins.
- Tune that resonance electrically using a force called spin-orbit torque, which nudges the electron spins into motion.
What they’re saying: “This gives us a quantum-scale stethoscope and control knob in one,” said Kelly Luo, co-corresponding author and Gabilan Assistant Professor of Physics and Astronomy, Chemistry, and Chemical Engineering and Materials Science at USC Dornsife. “We’re able to listen to the spin dynamics — and then dial them up or down — using nothing but electric current.”
How it’s different: Previous methods for detecting antiferromagnetic behavior relied on bulky lab equipment and relatively large materials. This new device works at the micron scale — roughly 1,000 times smaller — making it the most compact, electrically tunable platform yet.
- “We’ve shrunk the technology down to a size that makes practical applications possible,” said Daniel Ralph, co-corresponding author and R. Newman Professor of Physics in Cornell’s College of Arts and Sciences. “That’s what makes this so exciting.”
A clever twist: At first, the team couldn’t tell which of the two magnetic layers was responsible for the signal — their behaviors were too closely linked.
Their solution? Twist the layers ever so slightly to break the symmetry. That allowed them to target just one layer with electric current while leaving the other unaffected.
“It was like trying to separate the sound of two violins playing the same note,” said lead author Thow Min Jerald Cham, formerly at Cornell and now David and Ellen Lee Postdoctoral Scholar at Caltech. “That tiny shift helped us tell them apart and control each one individually.”
What’s next? The researchers plan to develop nano-oscillators based on their device — tiny components that generate ultra-fast signals for applications in medical imaging, scientific instruments, telecommunications, quantum computing and more.
- They also want to explore “negative damping” — a phenomenon where, instead of fading out, the spin oscillations actually gain energy. That could allow the device to act as a powerful, terahertz radiation source in a footprint smaller than a grain of sand.
About the study
In addition to Luo, Ralph and Cham, study authors include Xiaoxi Huang of Cornell; Daniel Chica and Xavier Roy of Columbia University; and Kenji Watanabe and Takashi Taniguchi of Japan’s National Institute for Materials Science.
Read more on the Cornell University College of Letters, Arts and Sciences’ news website.
Editor’s Note: Darrin S. Joy and Jim Key contributed to this article along with Linda B. Glaser of Cornell.