BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-1149
DTSTART:20080408T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260423T010348Z
LAST-MODIFIED:20080331T145621Z
LOCATION:5310 Chamberlin
SUMMARY:The Metal-Insulator Transition (MIT) in MgTi2O4 Spinel\, R. G.
  Herb Condensed Matter Seminar\, Stefano Leoni\, Max Planck - Dresden
DESCRIPTION:The study of transition metal oxide spinels represents a c
 onsiderable challenge for theory\, due to the richness of their proper
 ties and to their natural tendency to form ordered states upon phase t
 ransitions. MgTi2O4 for example undergoes a transition from a metallic
  to a spin-singlet insulator near Tc=260 K\, with the opening of an op
 tical gap and no sign of Drude weight. The metallic phase is character
 ized by a pyrochlore lattice occupied by Ti atoms. The transition to a
  tetragonal structure is accompanied by a selective shortening of some
  bonds under formation of 'molecular dimers'. In this talk we address 
 the problem of the origin of structural distortion in this material\, 
 by performing state-of-art correlated band structure calculations with
 in the LDA+ Hubbard U scheme. Therein we identify an orbital selective
  MIT that is carried by orbital rehybridization assisted by correlatio
 n\, without full orbital polarization. Additionally\, we derive the st
 ructural distortion by expressing the forces in the LDA+U potential an
 d by performing Parrinello-Rahman structure relaxation. Along this lin
 e we find a lock-in into a dimerized phase for a critical U value. Ref
 erence: S.Leoni\, A. Yaresko\, N. Perkins\, H. Rosner\, L. Craco\, sub
 mitted to PRL.
URL:https://www.physics.wisc.edu/events/?id=1149
END:VEVENT
END:VCALENDAR