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Seminario en 5 min
Estimados todos,
Les recordamos que el seminario del Dr. ValdÃs està por comenzar en 5 min.
Saludos
Nelly
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El Dr. Ortega me pidià avisarles que el seminario de maÃana jueves serÃ
presentado por el Dr. Rolando ValdÃs Aguilar, quien està concursando por una
plaza del laboratorio de Ãptica. EstÃn todos cordialmente invitados.
Saludos
Nelly
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Dr. Rolando ValdÃs Aguilar
"THz response and colossal magneto-electric effect in the topological
insulator Bi2Se3"
Resumen:
Ordered states of matter are typically categorized by their broken
symmetries. With the ordering of spins in a ferromagnet or the freezing of a
liquid into a solid, the loss of symmetry distinguishes the ordered state
from the disordered one. In contrast, topological states are distinguished
by specific topological properties that are encoded in their quantum
mechanical wave functions. Frequently, a consequence of these properties is
that there are robust topologically protected states on their boundaries.
The edge states of the quantum Hall effect (QHE) are the classic example.
In the last few years, it was realized that another class of such
topological matter may exist in 3D band insulators with large spin-orbit.
These so-called topological insulators are predicted to host robust surface
states, which exhibit a number of interesting properties including spin
helicity, immunity to back-scattering, and weak anti-localization. Here we
report the observation of an unprecedentedly large rotation of up to 65Â of
the polarization plane of linearly polarized light reflected (Kerr rotation)
from thin films of topological insulator Bi2Se3 in magnetic fields, which is
due almost entirely to the surface states. Our results are evidence for the
intrinsic response of the topologically protected surface states and
provide a benchmark for the magneto-electric effect predicted for these
materials.
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(Texto sin acentos)
Saludos
Nelly
--
C.P. Nelly Mellado
Asistente Ejecutivo de la Direccion
Instituto de Ciencias Fisicas
Apdo. Postal 48-3, 62251
Cuernavaca, Morelos; Mexico
Tel:+ 52 (777) 329-1745 y 329-1746
Red-UNAM: 27745 y 27746
Fax: (01-777) 317-5388
Cd. de Mexico: 5622-7745 y 46