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Past Seminar

Title              :

Ground state of the spin-1/2 Kagome antiferromagnet: A Contractor Renormalisation study

Speaker         : Ravi Chandra , NISER, Bhubaneswar
Date                : June 10, 2013
Time               : 12:00 PM
Venue            : Theory Seminar Room 3307
Abstract        :

We study the low energy phase of the nearest neighbour spin-1/2 Kagome antiferromagnet using Contractor Renormalisation (CORE). The lattice is analysed as a triangular lattice of the 12 site "Star of David" clusters. The two degenerate singlet ground states of the star clusters define an effective spin-1/2 degree of freedom. We construct an effective Hamiltonian till the third order in the CORE expansion, whose accuracy is verified using a comparison with Density Matrix Renormalisation Group calculations. We find a ground state phase which is translationally invariant. However, the spectrum of the CORE effective Hamiltonian exhibits a near exact double degeneracy which signals the onset of p6 chirality symmetry breaking in the thermodynamic limit. This phase and the effective Hamiltonian is analysed using a mean field theory. Addition of small further neighbour interactions is discussed.



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