Neutral Particles Behaving Like Metals: MagLab Reveals Hidden Quantum Structure in Electrical Insulator

Published December 19, 2025

Vacuum cell containing the custom-built nanocalorimeter (left) and a magnified view of the lithographically patterned sensor (right).

We discovered strong evidence for a brand-new kind of “electron-like” particle in an electrical insulator: it behaves like an electron in motion but carries no charge, meaning it can transport energy/information without ordinary electrical current — a potential pathway to radically lower-power electronics.

What is the finding

Scientists discovered that an electrical insulator, YbB₁₂, contains hidden particles that respond to magnetic fields even though they carry no electric charge. These “neutral fermions” revealed themselves through tiny ripples in the heat capacity when the material was placed in very strong magnetic fields.

Why is this important?

An insulator behaving like a metal is not expected, challenging long-standing ideas about how electrons behave in solids. Understanding these unusual particles may help scientists develop new theories for quantum materials. In the long term, insights from these systems could contribute to new technologies in electronics, sensing, and quantum information.

Who did the research?

Kuan-Wen Chen¹,; Yuan Zhu¹,; Danilo Ratkovski²; Guoxin Zheng¹; Dechen Zhang¹; Aaron Chan¹; Kaila Jenkins¹; Joanna Blawat³; Tomoya Asaba⁴; Fumitoshi Iga⁵; Chandra M. Varma⁶; Yuji Matsuda^4,7; John Singleton³; Alimamy F. Bangura²; Lu Li¹

¹University of Michigan, ²National MagLab, FSU. ³National MagLab, LANL, ⁴Kyoto University, ⁵Ibaraki University, ⁶University of California, Riverside, ⁷Los Alamos National Laboratory

Why did they need the MagLab?

Detecting these extremely small heat-capacity signals requires both very strong, stable magnetic fields and highly sensitive calorimetry. The MagLab’s DC-Field Facility is the only place where continuous magnetic fields above 35 tesla can be combined with precision nanocalorimetry—making this discovery possible. The MagLab’s unique environments allow scientists to uncover hidden states of matter that cannot be seen anywhere else.

Details for scientists

View or download the expert-level Science Highlight, Neutral Fermions Revealed by High-Field Heat Capacity in a Kondo Insulator
Read the full-length publication, Quantum Oscillations in the Heat Capacity of Kondo Insulator YbB₁₂, in Physical Review Letters

Funding

This research was funded by the following grants: K. M. Amm (NSF DMR-2128556); (NSF DMR-2317618; DOE DE-SC0020184; DOE BES “Science at 100 T”; Gordon and Betty Moore Foundation GBMF5305; JSPS KAKENHI 23H00089; JST CREST JPMJCR19T5)

For more information, contact Alimamy Bangura.

Tools They Used

This research was conducted in the 35 Tesla, 32 mm Bore Magnet and 41.5 Tesla, 32 mm Bore Magnet at the DC Field Facility - high-resolution nanocalorimetry. Magnetization measurements performed at PFF.