The Condensed Matter & Surface Sciences Colloquium Series presents Walter Lambrecht of Case Western Reserve University on “Electrons and Phonons in V2O5: a 2D Layered Material with 1D Chains and Strong Correlation Effect,” on Thursday, November 10, at 4:10 p.m. in Walter 245.
Walter Lambrecht
Abstract: 1D chains in each layer. In this talk, I will discuss how its electronic band structure is related to these low dimensional structural aspects and explore how it will change if one would be able to produce this material in atomically thin monolayer form. I will also discuss how the monolayer form affects the phonons.
We find interesting blue shifts of the highest vibrational modes, which we related to the reduction in screening in 2D. Our electronic structure calculations are done using the quasipartcile-selfconsistent GW method. Surprisingly, in this material, it is found that this method strongly overestimates the band gap and I will discuss potential sources of this error in the form of a lattice polarizaton effect as well as missing electron-hole interaction effects in GW. The most intriguing aspect of its band structure is that its lowest conduction band is split-off from the higher ones by about 1 eV. If this band becomes half-filled as in Na intercalated NaV2O5, interesting spin-polarization effects ensue. I will discuss the exchange interactions for this situation and show that if the system is slightly less than half-filled, the ordering of the spins would change from antiferromagnetic spins along the chains to ferromagnetically ordering.
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