A new approach to the Hubbard model

by Prof. Brijesh KUMAR ((New Dehli))

Tuesday 23 Jun 2009, 11:15 → 12:30 Europe/Zurich

EPFL, Salle 727 du BSP (Cubotron) (Lausanne)

In this talk, I will describe a new representation for electrons, in which, an electron is envisaged as a composite of a spinless fermion and the Pauli spin-1/2. Interestingly, this representation simplifies the Hubbard interaction. On a biparite lattice, at half filling, the Anderson superexchange correctly emerges within a simple decouppling of the Pauli spins from the spinless fermions. In the infinite U limit, the Hubbard model reduces to a particularly elegant form (reminiscent of the Anderson-Hasegawa double exchange problem) which so manifestly reveals the possibility of metallic magnetism (this is otherwise a very non-trivial problem as initiated by Nagaoka). I will further describe some exact calculations in 1d, and conclude with an over-view of the current work based on this representation. References: B. Kumar, Phys. Rev. B 77, 205115 (2008) B. Kumar, Phys. Rev. B 79, 155121 (2009)