BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2078
DTSTART:20110203T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260315T144757Z
LAST-MODIFIED:20110202T172459Z
LOCATION:5310 Chamberlin
SUMMARY:Two-dimensional electron gas with universal subbands at the su
 rface of SrTiO<sub>3</sub>\, R. G. Herb Condensed Matter Seminar\, And
 res Santander\, CSNSM - Université Paris-Sud\, France
DESCRIPTION:Similar to silicon that is the basis of conventional elect
 ronics\, strontium titanate (SrTiO<sub>3</sub>) is the bedrock of the 
 emerging field of oxide electronics. SrTiO<sub>3</sub> is the preferre
 d template to create exotic two-dimensional (2D) phases of electron ma
 tter at oxide interfaces\, exhibiting metal-insulator transitions\, su
 perconductivity\, or large negative magnetoresistance. However\, the p
 hysical nature of the electronic structure underlying these 2D electro
 n gases (2DEGs) remains elusive\, although its determination is crucia
 l to understand their remarkable properties. In this talk\, we present
  our angle-resolved photoemission spectroscopy (ARPES) results showing
  that there is a highly metallic universal 2DEG at the vacuum-cleaved 
 surface of SrTiO<sub>3</sub>\, independent of bulk carrier densities o
 ver more than seven decades\, including the undoped insulating materia
 l [1]. Our data unveil a remarkable electronic structure consisting on
  multiple subbands of heavy and light electrons. The analysis of the d
 ata shows that this 2DEG is confined within a region of ~5 unit cells 
 with a sheet carrier density of ~0.33 electrons per <i>a</i><sup>2</su
 p> (<i>a</i> is the cubic lattice parameter). The similarity of this 2
 DEG with those reported in SrTiO<sub>3</sub>-based heterostructures an
 d field-effect transistors suggests that different forms of electron c
 onfinement at the surface of SrTiO<sub>3</sub> lead to essentially the
  same 2DEG. Our discovery provides a model system for the study of the
  electronic structure of 2DEGs in SrTiO<sub>3</sub>-based devices\, an
 d a novel route to generate 2DEGs at surfaces of functional oxides.<br
 >
\n<br>
\n[1] A. F. Santander-Syro\, O. Copie\, T. Kondo\, <i>et al</
 i>. "Two-dimensional electron gas with universal subbands at the surfa
 ce of SrTiO<sub>3</sub>". Nature 469\, 189 (2011).
URL:https://www.physics.wisc.edu/events/?id=2078
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