[LA-SiGMA] LASiGMA Seminar Today - J.W. Allen, 3:30pm (Please see new broadcast information)

[shelley lee]

Dear All,

As a reminder, Dr. J.W. Allen will be giving a talk today at 3:30pm, 1008B,
Digital Media Center, Louisiana State University. The title of his talk is "
Topologically protected surface conduction in SmB6 – new solution to a
thirty year old mystery."

Abstract:
The paradigm mixed valence insulator SmB6, exhibits a mysterious residual
metallic conductivity at low temperatures (T < 4 K) [1], with a value too
small to explain within the framework of three-dimensional extrinsic [1] or
intrinsic [2] bulk conduction. All efforts to eliminate this residual
conductivity have failed. It has recently been shown that the symmetry
requirements for a bulk single particle gap in SmB6 [3] also satisfy the
requirements for the protected surface states of a topological insulator
(TI) [4]. I will describe recent transport [5] and de Haas van Alphen [6]
experiments at the University of Michigan, angle resolved photoemission
spectroscopy at the Advanced Light Source [7], and, as time permits, other
work, showing that SmB6 is indeed a TI material. These new findings resolve
in an elegant way the 30 year old transport mystery of SmB6, provide a
material in which the dc transport properties of a 3D topological state can
be directly studied, and generally point the way to the exploration of
topological symmetries in strongly correlated electron materials.

Biography:
James W. Allen was born in Livingston, Montana, USA in 1941.  He received
his B.S. (1963, with distinction) and Ph.D. (1968) degrees from Stanford
University.  He joined the research staff of the M.I.T. Lincoln Laboratory
in 1968, moved to the Xerox Palo Alto Research Center in 1973, and became
Professor Physics at the University of Michigan in 1987.  He served as the
Associate Chair for the Physics Graduate Program from 1990 to 1993, was the
Joachin M. Luttinger Collegiate Professor of Physics from 2004-2010, and
since then has been Professor Emeritus of Physics.  He has been an academic
guest at the Swiss Federal Technical Institute at Zurich, the Max Planck
Institute for Solid State Physics at Stuttgart, the University of Groningen,
the European Synchrotron Radiation Center at Grenoble, the Advanced Light
Source at Berkeley and the Max Planck Institute for Chemical Physics of
Solids, Dresden.  He received a Senior U.S. Scientist Award of the Alexander
von Humboldt Foundation (1989) and is a Fellow of the American Physical
Society (1990).  He has served as a Divisional Associate Editor of Physical
Review Letters (1992-95).  Three of his papers have been included in issues
of the Physical Society of Japan’s “Series of Selected Papers in Physics.”
In 2002 he was awarded the Frank Isakson Prize of the American Physical
Society for his contributions to the field of spectroscopy in strongly
correlated electron systems, a field in which he continues to be an active
researcher.

References
[1] J. W. Allen, B. Batlogg and P. Wachter, Phys. Rev. B 20, 4807 (1979).
[2] J. C. Cooley, M. C. Aronson, Z. Fisk, and P. C. Canfield, Phys. Rev.
Lett. 74, 1629 (1995).
[3] R. M. Martin and J. W. Allen, in Valence Fluctuations in Solids, edited
by L. M. Falicov, W. Hanke, and M. B. Maple (North-Holland, Amsterdam,
1981), page 85.
[4] M. Dzero, K. Sun, V. Galitski and P. Coleman, Phys. Rev. Lett. 104,
106408 (2010).
[5] S. Wolgast, Ç. Kurdak, K. Sun, J. W. Allen, D. J. Kim and Z. Fisk, Phys.
Rev. B 88, 180405(R) (2013).
[6] G. Li, Z. Xiang, F. Yu, T. Asaba, B. Lawson, P. Cai, C. Tinsman, A.
Berkley, S. Wolgast, Y. S. Eo, Dae-Jeong Kim, C. Kurdak, J. W. Allen, K.
Sun, X. H. Chen, Y. Y. Wang, Z. Fisk, and Lu Li, arXiv: 1306.5221 (2013).
[7] J. D. Denlinger, J. W. Allen, J.-S. Kang, K. Sun, J.-W. Kim, J.H. Shim,
B. I. Min, Dae-Jeong Kim, Z. Fisk, arXiv:1312.6637 (2014)

Also available on site at the locations below.
UNO – 234, Liberal Arts Building
LATech – 122, Nethken Hall
SUBR – 211 J.B. Moore Hall
Xavier – 226 Qatar Pavillion

Please note, this seminar will ONLY be accessible through HD
videoconferencing. Adobe connect will NOT be offered.

Regards,
Shelley Lee
Project Coordinator
225-578-0465




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