Resolving the chicken-and-egg problem in VO2

A new paradigm for the Mott transition

Óscar Nájera1, M. Civelli1,
V. Dobrosavljević2, M. J. Rozenberg1

najera.oscar@gmail.com / Titan-C

1 Laboratoire de Physique des Solides, CNRS-UMR8502, Université Paris-Sud, Orsay 91405, France
2 Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306, USA

March 13, 2017 - New Orleans

The transition in VO2

Sorry, your browser does not support SVG. Sorry, your browser does not support SVG.

Peierls vs Mott

Outline

  • Solve using DMFT a reference model: The Dimer Hubbard Model
  • Characterize the correlated Insulator to correlated Metal transition
  • Dimer-Mott Transition explains key experiments in the transition of VO2

Dynamical Mean Field Theory (DMFT)

Sorry, your browser does not support SVG.

  • Same cluster impurity problem as other LDA+DMFT studies for VO2
  • Solved Exactly in the Bethe Lattice
  • DMFT Exact by construction in the large coordination limit
  • DMFT yields generic behavior of a high-dimensional lattice

DMFT Phase diagram at \(T=0\)

Sorry, your browser does not support SVG.

Reference Mott transition: V\(_2\)O3

Sorry, your browser does not support SVG.

The case \(t_\perp/D=0\) no dimers

The Dimer-Mott transition: VO2

Sorry, your browser does not support SVG.

The dimerized \(t_\perp/D=0.3\) lattice

The Effect of correlation is to enhance dimerization

Sorry, your browser does not support SVG.

Electronic Structure

Sorry, your browser does not support SVG.

Mid Infrared Peak appears in Correlated Metal

Sorry, your browser does not support SVG.

Optical conductivity at the transition

SNIM-heat.jpg Sorry, your browser does not support SVG.

Conclusions

  • The Dimer Hubbard Model describes a temperature driven insulator to metal correlated transition
  • These results explain key observations in the transition in VO2: the Mid-Infrared features in the optical conductivity before the structural transition takes place
  • The existence of a metastable correlated dimer metal phase is the key ingredient that shows that the VO2 Insulator Metal transition is electronically driven(Dimer Mott Mechanism)
  • Read more about our work in: O. Nájera, et al. (2017). PRB, 95(3), 035113

Optics Support

vo2_lowe_optics_qa_sci.jpg Optical conductivity at the transition