Presented By: Applied Physics
Applied Physics Seminar: "Metal or insulator? That is the question."
Lu Li, Associate Chair, Department of Physics and Professor of Physics, College of Literature, Science, and the Arts, University of Michigan
Abstract:
Lu will talk about the dual nature of the topological Kondo insulators. They are perfect insulators like pure silicon, and their electrical resistivity diverges by more than a million times during cooling down. Yet, they show a characteristic feature of good metal---oscillations in magnetization under magnetic fields.
In this talk, Lu will review his discovery of this contradiction: his quest to observe insulators’ oscillations, not only in magnetization but also in electrical resistivity. His experiments demonstrate that the oscillatory carriers are just like electrons, following the Fermi-Dirac distributions, even in this perfect insulator. So, can the compound be both metal and insulator? Or can a fermion exist in solids even without electrical charge? Let's find the answer.
References:
[1] Xiang, Z. et al. Quantum oscillations of electrical resistivity in an insulator. Science 362, 65 (2018).
[2] Li, Lu et al. Emergent mystery in the Kondo insulator samarium hexaboride, Nature Review Physics 2, 463 (2020).
[3] Sato, Y. et al. Unconventional thermal metallic state of charge neutral fermions in an insulator. Nature Physics 15, 954 (2019).
[4] Xiang, Z., et al. Unusual high-field metal in a Kondo insulator. Nature Physics 17, 788 (2021).
Lu will talk about the dual nature of the topological Kondo insulators. They are perfect insulators like pure silicon, and their electrical resistivity diverges by more than a million times during cooling down. Yet, they show a characteristic feature of good metal---oscillations in magnetization under magnetic fields.
In this talk, Lu will review his discovery of this contradiction: his quest to observe insulators’ oscillations, not only in magnetization but also in electrical resistivity. His experiments demonstrate that the oscillatory carriers are just like electrons, following the Fermi-Dirac distributions, even in this perfect insulator. So, can the compound be both metal and insulator? Or can a fermion exist in solids even without electrical charge? Let's find the answer.
References:
[1] Xiang, Z. et al. Quantum oscillations of electrical resistivity in an insulator. Science 362, 65 (2018).
[2] Li, Lu et al. Emergent mystery in the Kondo insulator samarium hexaboride, Nature Review Physics 2, 463 (2020).
[3] Sato, Y. et al. Unconventional thermal metallic state of charge neutral fermions in an insulator. Nature Physics 15, 954 (2019).
[4] Xiang, Z., et al. Unusual high-field metal in a Kondo insulator. Nature Physics 17, 788 (2021).
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