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UID:UW-Physics-Event-2798
DTSTART:20121008T213000Z
DURATION:PT1H0M0S
DTSTAMP:20240329T061044Z
LAST-MODIFIED:20121008T163500Z
LOCATION:5310 Chamberlin
SUMMARY:Electronic properties of ultimate nanowires\, Condensed Matter
Theory Group Seminar\, Franz Himpsel
DESCRIPTION:Stepped semiconductor surfaces decorated with metal atoms
make it possible to engineer the ultimate nanowire\, a string of atoms
connected by a single wave function. Such atomic wires form spontaneo
usly for many metal-semiconductor combinations and thereby provide a p
layground for low-dimensional electron physics [1]. Angle-resolved pho
toelectron spectroscopy combined with scanning tunneling microscopy/sp
ectroscopy reveals a variety of unexpected phenomena\, such as atomica
lly-precise ribbons of graphitic silicon and spin-polarized Fermi surf
aces caused by the Rashba effect.
\n
\nThe broken bond orbital
s are so localized at the step edges that they become fully spin-polar
ized\, similar to isolated broken bonds (Pb centers). Density function
al theory predicts a spin-polarized ground state which is closely coup
led to the formation of a superlattice (neither can exist without the
other) [2]. This resembles the situation in complex oxides (HiTc super
conductors\, multiferroics)\, where the spin\, charge\, and lattice de
grees of freedom are strongly coupled and make it difficult to find a
simple approximation of their electronic structure.
\n
\nTwo-p
hoton photoemission spectroscopy [3] and scanning tunneling spectrosco
py [4] provide support for spin-polarized silicon atoms by probing the
ir characteristic minority spin state.
\n
\n
\nREFERENC
ES
\n
\n1. I. Barke et al.\, Low-dimensional electron gas
at semiconductor surfaces\, Solid State Commun. 142\, 617 (2007)\;
\n Nuri Oncel\, Atomic chains on surfaces\, J. Phys. C
ondens. Matter 20\, 393001 (2008)\;
\n J. Schaefer et al.\, <
i>Self-organized atomic nanowires of noble metals on Ge(001): atomic s
tructure and electronic properties\, New Journal of Physics 11\, 1
25011 (2009)\;
\n P. C. Snijders and H. H. Weitering\, Elect
ronic instabilities in self-assembled atom wires\, Rev. Mod. Phys.
82\, 307 (2010).
\n2. S. C. Erwin and F. J. Himpsel\, Intrinsic
magnetism at silicon surfaces\, Nature Communications 1:58 (2010).
\n3. K. Biedermann et al.\, Spin-split silicon states at step edges
of Si(553)-Au\, Phys. Rev. B 85\, 245413 (2012).
\n4. P. C. Snij
ders et al.\, Spectroscopic evidence for spin-polarized silicon atoms
on Si(553)-Au\, submitted.
\n
\n
URL:https://www.physics.wisc.edu/events/?id=2798
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