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SUMMARY:First order insulator-metal transition at the LaAlO3 / SrTiO3 inte
 rface - Danny Bennett
DTSTART:20191016T103000Z
DTEND:20191016T113000Z
UID:TALK131983@talks.cam.ac.uk
CONTACT:77905
DESCRIPTION:Perovskite materials exhibit many interesting structural and e
 lectronic effects such as ferroelectric domains\, tilting octahedral oxyge
 n cages and two-dimensional electron gas (2DEG) formation at interfaces be
 tween different materials [1]. The standard theories which describe these 
 effects are uncoupled and thus cannot describe the competition between the
 m. In this work\, we introduce theories which couple these effects and stu
 dy their competition and coexistence. By coupling the theories for ferroel
 ectric domains and 2DEGs in PbTiO3 (PTO) thin films [2] and PbTiO3/SrTiO3 
 (PTO/STO) superlattices\, we find that there are situations in which both 
 can be observed simultaneously. The formation of the 2DEG at the LaAlO3/Sr
 TiO3 (LAO/STO) is regarded as continuous\, as described by the standard th
 eory [3]. We show that by coupling this 2DEG to tilts in the materials\, i
 t is possible to observe a first order phase transition\, and even two pha
 se transitions\, with the application of an external electric field.\n\nI 
 will also discuss our first-principles calculations to observe these phase
  transitions using density functional theory.\n\n[1] A. Ohtomo and H. Hwan
 g\, Nature 427\, 6973 (2004)\n[2] P. Aguado-Puente et al.\, Physical Revie
 w B 92\, 035438 (2015)\n[3] N. Bristowe et al.\, Journal of Physics: Conde
 nsed Matter 26\, 143201 (2014)
LOCATION:Mott Seminar Room\, Cavendish Laboratory
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