Researchers at the University of Michigan have made a significant discovery in the field of quantum physics, revealing unexpected oscillations within an insulating material. This finding challenges long-held assumptions regarding the behavior of insulators and offers new insights into material science. The work, conducted at the National Magnetic Field Laboratory, suggests that these quantum oscillations originate within the bulk of the material rather than at its surface, indicating a potential for materials to exhibit dual properties.
The research, recently published in Physical Review Letters, was led by physicist Lu Li and a dedicated team of international scientists. They explored a puzzling phenomenon known as quantum oscillations, typically observed in metals where electrons behave like tiny springs in response to magnetic fields. In contrast, oscillations had also been detected in insulators, leading to ongoing debates about their origins—whether they are surface-level effects or intrinsic properties of the material.
Investigating the Core of Quantum Mechanics
Li and his colleagues aimed to clarify this uncertainty by utilizing the world’s most powerful magnets at the National Magnetic Field Laboratory. Their experiments provided clear evidence that the quantum oscillations stem from the bulk of the insulating material, not merely the surface. “I wish I knew what to do with that, but at this stage we have no idea,” Li commented. “What we have right now is experimental evidence of a remarkable phenomenon.”
The study brought together more than a dozen scientists from six institutions, including research fellow Kuan-Wen Chen and graduate students from the University of Michigan. Chen noted the significance of their findings: “We are excited to provide clear evidence that it is bulk and intrinsic,” he stated, addressing a long-standing question regarding the source of carriers in these exotic insulators.
A New Duality in Material Properties
Li describes this discovery as indicative of a “new duality” in materials science. Traditionally, physics recognized a duality in which light and matter can behave as both waves and particles. Li’s team posits that certain materials may now show dual behavior, acting as both conductors and insulators. They conducted their experiments using a compound known as ytterbium boride (YbB12), under an astonishing magnetic field of 35 Tesla, which is approximately 35 times stronger than that of a standard hospital MRI machine.
“Effectively, we’re showing that this naive picture where we envisioned a surface with good conduction that’s feasible to use in electronics is completely wrong,” Li explained. “It’s the whole compound that behaves like a metal even though it’s an insulator.” This finding, although only observable under extreme conditions, raises essential questions about how materials function at the quantum level.
The implications of this research extend beyond theoretical physics. By confirming that the oscillations are intrinsic to the material, the researchers hope to inspire further experimental and theoretical work that could unlock new technological applications. “We don’t yet know what kind of neutral particles are responsible for the observation,” said graduate student Yuan Zhu, expressing hope that this discovery will drive additional inquiry into the properties of such materials.
The research received support from the U.S. National Science Foundation, the U.S. Department of Energy, the Institute for Complex Adaptive Matter, the Gordon and Betty Moore Foundation, and both the Japan Society for the Promotion of Science and the Japan Science and Technology Agency. This collaboration highlights the global effort to unravel the complex behaviors of materials at the quantum scale, setting the stage for future advancements in the field.
