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August 30, 2013 >>
|Friday, August 30|
Condensed Matter Seminar, Xi Dai, "Topological phases in mix valence compounds"
In this talk, I will propose that the mix valence phenomena in some of the rare earth compounds
will naturally lead to non-trivial topology in band structure.One of the typical example is SmB6,
where the intermediate valence of Sm generates band inversion at the X point and the non-trivial
Z2 index. Other than SmB6, YbB6 and YbB12 are both mix valence compounds. By applying
LDA+Gutzwiller to these materials, we find that YbB6 has non-trivial Z2 index, indicating that YbB6 is another three dimensional topological insulator with strong correlation effects. Our calculation also finds that YbB12 is a trivial insulator in the sense of Z2 but it can be classified as topological crystalline
insulator with non-zero mirror Chern number. The electronic structure at finite temperature
has also been studied using LDA+DMFT, indicating YbB6 is still in the mix valence region while
YbB12 is quite close to the Kondo limit.
PCTS Seminar Room · 2:00 p.m.– 4:00 p.m.