專題演講 Seminar

2022/12/01(Thu)     10:30 -12:00    五樓第一會議室5th Floor(1st meeting room)
視訊演講 Video Seminar [ Meeting Link / ID: 2515 111 5432 / Password: 123456 ]

Title

Probing anomalous metallic behaviour near metal-insulator transitions in quantum materials

Speaker

徐有德博士 (Department of Correlated Electron Systems, High Field Magnet Laboratory, Radboud University)

Dr. Yu-Te Hsu (Department of Correlated Electron Systems, High Field Magnet Laboratory, Radboud University)

Abstract

The interactions among the macroscopic number of electrons in crystalline solids can lead to emergence of
new states of matter that cannot be described by the properties of the individual constituents. Quantum
materials, in which ‘emergent’ phenomena are manifest, have become a recent focus of condensed matter
research. In this talk, I will review recent experimental discoveries of anomalous metallic behaviour in
materials on the brink of metal-insulator transitions, probed via high magnetic fields created in highly
controlled environments. In SmB6, an archetypal Kondo insulator with 4f electrons, the observation of
magnetic quantum oscillations indicates the existence of a coherent Fermi surface within its insulating bulk
[1], challenging the established distinction between a metallic and insulating state within the Landau-Fermi
liquid paradigm. In the cuprate superconductor YBa2Cu3O6+x with a Mott-insulating parent state, definite
signatures of Fermi surface and superconductivity are found to coexist in the underdoped regime [2],
contrasting the strange metallic states with T-linear resistivity and H-linear magnetoresistance in the
overdoped side [3]. Lastly, I will present new results of magnetotransport studies on infinite-layer nickelates,
which reveal the anomalous metallic behaviour in this new model system for the study of unconventional
superconductivity [4]. These results highlight the approach of exposing materials near metal-insulator
transitions to high magnetic fields as a promising avenue for discoveries in quantum solids.
Reference
[1] Tan et al., Science 349, 287 (2015)
[2] Hsu et al., PNAS 118, e2021216118 (2021)
[3] Ayres et al., Nature 595, 661 (2021)
[4] Hsu et al., Phys. Rev. Res. 3, L042015 (2021)
Biography
Dr Hsu received his BSc in Materials Science and Engineering from National Tsing Hua University in
Taiwan, MS in Materials Physics from Linköping University in Sweden, and PhD in Physics from
Cambridge University in the UK. In 2018 He moved to the High Field Magnet Laboratory at Radboud
University in Nijmegen, the Netherlands as a postdoc researcher, and he is currently a research scientist at
Radboud University working with Prof. Nigel Hussey. His current research interests include complex oxides,
unconventional superconductivity, topological transport, and developing high-sensitivity experiments under
high magnetic fields. (Agenda)

Language

演講語言 (Language): in English