Here\u2019s what you\u2019ll learn when you read this story:<\/p>\n
For more than seven years, scientists at the University of Michigan have explored the strange quantum oscillations of the Kondo insulator ytterbium boride (YbB12).<\/p>\n
In 2018, the team discovered that quantum oscillations arose from the bulk of the insulator under intense magnetic fields, which is counter to the behavior of a type of well-known material known as a topological insulator.<\/p>\n
A new study\u2014leveraging powerful magnets at the National Magnetic Field Laboratory\u2014confirms that these oscillations are intrinsic and occur in the insulating bulk of the material, leading to questions about what practical purpose this \u201cbizarre\u201d quantum behavior could serve.<\/p>\n
Some of history\u2019s biggest discoveries initially appear to serve no practical purpose. When scientists devised the first working lasers a few decades after Albert Einstein\u2019s<\/a> theory of stimulated emission in 1917, few understood what practical applications<\/a> they might have. Now, of course, most of the technological world relies on them.<\/p>\n And it doesn\u2019t stop at lasers. Lu Li from the University of Michigan has spent years exploring a strange quantum<\/a> behavior in the insulator known as ytterbium boride (YbB12), which is also known as a \u201cKondo insulator.\u201d In 2018, Li and his team published a paper in Science<\/a> detailing a strange phenomenon regarding YbB12. While its surface acts as a conductor, its bulk (or interior) acts as an insulator\u2014but the team found evidence of quantum oscillations in the material\u2019s bulk, aligning with previous research conducted by scientists at the University of Cambridge years earlier<\/a>.<\/p>\n \u201cThis result confirms that Kondo insulators have a dual nature\u2014they are both electrical insulators and itinerant metals<\/a>,\u201d Li told Physics World<\/a> at the time. \u201cThis duality is a surprising consequence of the strong correlations between the electrons in the material.\u201d<\/p>\n Fast forward seven years later, and Li and his team have gathered even more evidence of this striking quantum behavior in a study published in the journal Physical Review Letters<\/a>. Working at the most powerful magnet<\/a> lab in the world\u2014the National Magnetic Field Laboratory in Tallahassee, Florida\u2014Li aimed to confirm that these oscillations did indeed form within the bulk of the insulator and that they were intrinsic to the material.<\/p>\n \u201cThe community has not yet reached a consensus on fundamental questionsabout the quantum oscillations; debates persist about whether the oscillations originate from the surface or the bulk and whether they are intrinsic or extrinsic,\u201d the authors wrote. \u201cIt is essential to obtain direct thermodynamic<\/a> evidence to determine whether the [\u2026] thermal properties originate from the same quasiparticle band as the quantum oscillations.\u201d<\/p>\n While this study confirms the intrinsic bulk origins of these quantum oscillations, the authors note that this behavior only arises in magnetic fields at the threshold of 35 Tesla. For comparison, an MRI machine<\/a> only leverages a magnetic field of one Tesla. Admittedly, Li said he isn\u2019t quite sure where this new discovery leads the field. Topological insulators\u2014materials that are conductive on their surface, but insulators in their bulk\u2014have enabled new quantum technologies<\/a>, but a material where quantum oscillations occur in the bulk is a still a bit of a question mark.<\/p>\n