University at Buffalo physicists are proposing a quantum sensing system that could simplify the identification of altermagnets, a recently discovered third category of magnetism potentially combining the strengths of both ferromagnets and antiferromagnets. For nearly a century, these two types of magnets defined the field; however, Libor Šmejkal and Jairo Sinova of Johannes Gutenberg University of Mainz first proposed altermagnets after encountering an effect they couldn’t explain. Altermagnets may offer a path toward faster, more energy-efficient electronics. The proposed technique measures how a tiny magnetic defect in a nearby diamond responds to an altermagnet’s presence, analyzing the relaxation of its magnetic signal. “This could be the first building block of a new generation of experiments that determine whether a material is an altermagnet,” says corresponding author Jamir Marino, PhD, assistant professor in the UB Department of Physics, adding that confirming the theory is crucial to unlocking altermagnets’ potential to revolutionize how we transport information.
Altermagnetism Emerges: Combining Ferromagnetic and Antiferromagnetic Traits
Beyond ferromagnets and antiferromagnets, altermagnetism is gaining traction as a potential component of future electronics. The Mainz team first proposed altermagnets after observing an effect they could not explain using either ferromagnets or antiferromagnets. Theoretical calculations suggest more than 200 materials may be altermagnetic, more than double the number of known ferromagnetic materials. This approach aims to minimize disturbance to the material being studied, ensuring a more accurate reading of its intrinsic magnetic properties. “You don’t want your measurement to strongly perturb the material you’re studying because it can become harder to tell whether you’re seeing the material’s natural behavior or behavior caused by the experiment,” Marino adds. “This sensing technique could become an important tool for exploring candidate altermagnetic materials,” Sinova says, highlighting the potential for this system to advance the field. Altermagnets exhibit a complex atomic structure where overall magnetism cancels out, similar to antiferromagnets, yet retain electronic behaviors typically associated with ferromagnets, potentially combining the best attributes of both.
Quantum Sensing Technique Detects Altermagnetic Spin Relaxation
Researchers are now focused on reliable detection methods. This approach differs from conventional methods by minimizing disruption to the material being examined, a critical factor in obtaining accurate readings. The diamond defect, created by a nitrogen atom replacing a carbon atom, acts as an extraordinarily sensitive probe of surrounding magnetic behavior; researchers would measure the relaxation rate of its spin in various directions, looking for patterns indicative of an altermagnetic structure. This theoretical technique is not without its hurdles, as Marino acknowledges that experiments are still needed to validate its reliability. However, efficiently identifying altermagnetic materials is seen as a crucial step toward realizing their potential in next-generation electronics, potentially leading to smaller, less power-hungry devices.
This could be the first building block of a new generation of experiments that determine whether a material is an altermagnet.
Jamir Marino, PhD, assistant professor in the UB Department of Physics, College of Arts and Sciences
Ruthenium Dioxide Discovery Initiated Altermagnetism Research
Their calculations revealed the compound exhibited no net magnetization, a characteristic of antiferromagnets, yet responded to electric current like a ferromagnet, prompting the conceptualization of altermagnetism. This discovery, occurring within the last decade, expanded the known magnetic landscape beyond ferromagnets and antiferromagnets, potentially offering a pathway to faster, more energy-efficient electronics. Now, physicists at Buffalo are detailing a quantum sensing system designed to streamline the identification of these elusive altermagnets. The proposed technique centers on measuring the relaxation of a magnetic signal emanating from a tiny defect within a nearby diamond; the rate and pattern of this relaxation could serve as a fingerprint for altermagnetic behavior. The system’s design prioritizes minimal disruption to the material under investigation, a key advantage over conventional methods. While currently theoretical, relying on advanced quantum dynamic simulations, the approach offers a promising avenue for validating the existence of altermagnetism in more than 200 materials, more than double the number of known ferromagnetic materials, and ultimately, harnessing their unique properties for technological advancement.
That arrangement allows altermagnets to combine the rapid switching behavior of antiferromagnets with some of the more easily controllable electronic properties of ferromagnets.
