学术沙龙（5月16日 14:30-16:30）

主持人：王猛 教授

欢迎广大师生前来参与！

【摘要】

Considerable excitement was generated by the observation of large and linear positive

magnetoresistance (MR) in non-magnetic silver chalcogenides. Renewed interest in these

materials was kindled by the discovery that Ag2Te in particular is a topological insulator with

gapless linear Dirac-type surface states. High-pressure x-ray diffraction studies, combined with

first-principles electronic structure calculations, have identified three phase transitions as the

pressure is increased: an isostructural transition identified with an electronic topological transition

followed by two structural phase transitions. These recent studies were carried out on nominally

stoichiometric Ag2Te. For the present work we have prepared single-phase self-doped Ag2-dTe

samples with a well-characterized silver deficit (d = 2.0′10-4) for structural and electrical transport

measurements over extended ranges of pressure (0-43 GPa), temperature (2-300 K) and magnetic

field (0-9 T). The temperature dependence of the resistivity exhibits anomalous behavior at 2.3

GPa, slightly above the isostructural transition, which we postulate is due to Fermi surface

reconstruction associated with a charge-density-wave (CDW) phase. The anomaly is enhanced by

the application of a 9T magnetic field and shifted to higher temperature, implying that the

electronic Zeeman energy is sufficient to alter the gapping of the Fermi surface. A peak in the

pressure dependence of the resistivity and a sudden drop in the pressure dependence of the

mobility, occurring at 2.3 GPa, provide additional evidence for a CDW phase at pressures slightly

above the isostructural transition.

【报告人简介】

Marie-Louise Saboungi is Full Professor of Condensed Matter Physics at the French Universities
and conducts her research at the Sorbonne Université in Paris. She served as Director of a
research institute in Orleans (CRMD) for 10 years and as Co-Director of the Materials, Energy
and Geosciences Thrust Area at Orleans. Prior to that she was a Senior Scientist at Argonne 
National Laboratory near Chicago, where she established close collaborations with the University 
of Chicago’s James Franck Institute and with Cornell University’s Food Sciences Department. 
She is a Fellow of the American Association for the Advancement of Science, the American 
Physical Society and the Alexander von Humboldt Foundation, from which she received the
Helmholtz-Humboldt Prize in 2008. She has served on international advisory committees as well 
as national committees in the US for DOE and the NSF, in France for the CNRS, ANR and 
AERES, and in the European Community where she served on the FET Advisory Board for 
Horizon 2020. She has organized and chaired over fifty international conferences and workshops 
including two Gordon Research Conferences in the United States. She actively participated in
the Association of Women in Science and received an Award for Leadership in the Professions 
from the YWCA of Metropolitan Chicago. She has twice been awarded grants for senior visitors
from the Japan Society for the Promotion of Science and a research fellowship from the
Ikerbasque Foundation in Spain. She was a visiting Chair Professor at FUNSOM Soochow, China 
for three years. At present she is involved in investigating complex soft materials with a special 
interest in the thermal, magnetic and biomedical properties of functionalized nanomaterials with
a view to applications in energy and biotechnology.