BEGIN:VCALENDAR VERSION:2.0 PRODID:Data::ICal 0.22 BEGIN:VEVENT DESCRIPTION:Hitesh J. Changlani\, Florida State University\n\n
Strongly correlated systems provide a fertile ground for dis covering exotic states of matter\, such as those with topologically non-tr ivial properties. Among these are geometrically frustrated magnets\, which harbor spin liquid phases with fractional excitations.
\n\nOn the experimental front\, this has motiva ted the search for new low dimensional quantum materials and on the theore tical front\, this area of research has led to analytical and numerical ad vances in the study of quantum many-body systems.
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\n\nI present aspects of our theoretical and numerical work in the area of frustrated magnetism\, focusing on the frustrated kagome geometry\ , which has seen a flurry of research activity owing to several near-ideal material realizations. On the theoretical front\, the kagome problem has a rich history and poses multiple theoretical puzzles which continue to ba ffle the community. First\, I present a study of the spin-1 antiferromagne t\, where our numerical calculations indicate that the ground state is a t rimerized valence bond (simplex) solid with a spin gap [1]\, contrary to p revious proposals. I show evidence from recent experiments that support ou r findings but also pose new questions. The second part of the talk follow s from an unexpected outcome of my general investigations in the area for the well-studied spin-1/2 case [2]. I explain the existence of an exactly solvable point in the XXZ-Heisenberg model for the ratio of Ising to trans verse coupling $J_z/J=-1/2$ [3]. This point in the phase diagram\, previou sly unreported in the literature\, has "\;three-coloring"\; states as its exact quantum ground states and is macroscopically degenerate. It exists for all magnetizations and is the origin or "\;mother"\; of many of the observed phases of the kagome antiferromagnet. I revisit aspe cts of the contentious and experimentally relevant Heisenberg case and dis cuss its relationship to the newly discovered point [3\,4].
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\n[1] H. J. Changlani\, A.M. Lauc
hli\, Phys. Rev. B 91\, 100407(R) (2015).
\n[2] K. Kumar\, H. J. Chan
glani\, B. K. Clark\, E. Fradkin\, Phys. Rev. B 94\, 134410 (2016).
[3] H. J. Changlani\, D. Kochkov \, K. Kumar\, B. K. Clark\, E. Fradkin\, Phys. Rev. Lett. 120\, 117202 (20 18).
\n\n[4] H. J. Changlani\,
S. Pujari\, C.M. Chung\, B. K. Clark\, under preparation. <
/p>\n
DTSTART:20180831T193000Z
LOCATION:Physics Building\, Room 204
SUMMARY:The mother of all states of the kagome quantum antiferromagnet
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