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UID:UW-Physics-Event-2798
DTSTART:20121008T213000Z
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DTSTAMP:20260420T022003Z
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.<br>
\n<br>
\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.<br>
\n<br>
\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. <br>
\n <br>
\n <br>
\nREFERENC
 ES<br>
\n<br>
\n1.  I. Barke et al.\, <i>Low-dimensional electron gas 
 at semiconductor surfaces</i>\, Solid State Commun. 142\, 617 (2007)\;
  <br>
\n    Nuri Oncel\, <i>Atomic chains on surfaces</i>\, J. Phys. C
 ondens. Matter 20\,  393001 (2008)\; <br>
\n    J. Schaefer et al.\, <
 i>Self-organized atomic nanowires of noble metals on Ge(001): atomic s
 tructure and electronic properties</i>\, New Journal of Physics 11\, 1
 25011 (2009)\;<br>
\n    P. C. Snijders and H. H. Weitering\, <i>Elect
 ronic instabilities in self-assembled atom wires</i>\, Rev. Mod. Phys.
   82\, 307 (2010).<br>
\n2.  S. C. Erwin and F. J. Himpsel\, Intrinsic
  magnetism at silicon surfaces\, Nature Communications 1:58 (2010).<br
 >
\n3.  K. Biedermann et al.\, Spin-split silicon states at step edges
  of Si(553)-Au\, Phys. Rev. B 85\, 245413 (2012).<br>
\n4.  P. C. Snij
 ders et al.\, Spectroscopic evidence for spin-polarized silicon atoms 
 on Si(553)-Au\, submitted.<br>
\n<br>
\n
URL:https://www.physics.wisc.edu/events/?id=2798
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