Copyright (c) 2010 All rights reserved. http://works.bepress.com/rahul_hardikar Recent documents in Rahul Hardikar en-us Wed, 14 Apr 2010 01:31:32 PDT 3600 http://works.bepress.com/rahul_hardikar/4 http://works.bepress.com/rahul_hardikar/4 Mon, 12 Apr 2010 09:19:30 PDT R. T. Clay http://works.bepress.com/rahul_hardikar/3 http://works.bepress.com/rahul_hardikar/3 Mon, 12 Apr 2010 09:18:12 PDT Rahul Hardikar http://works.bepress.com/rahul_hardikar/2 http://works.bepress.com/rahul_hardikar/2 Mon, 12 Apr 2010 09:16:52 PDT R. T. Clay http://works.bepress.com/rahul_hardikar/1 http://works.bepress.com/rahul_hardikar/1 Sat, 10 Oct 2009 14:41:12 PDT It is known that within the interacting electron model Hamiltonian for the one-dimensional (1/4)-filled band, the singlet ground state is a Wigner crystal only if the nearest-neighbor electron-electron repulsion is larger than a critical value. We show that this critical nearest-neighbor Coulomb interaction is different for each spin subspace, with the critical value decreasing with increasing spin. As a consequence, with the lowering of temperature, there can occur a transition from a Wigner crystal charge-ordered state to a spin-Peierls state that is a bond-charge-density wave with charge occupancies different from the Wigner crystal. This transition is possible because spin excitations from the spin-Peierls state in the (1/4)-filled band are necessarily accompanied by changes in site charge densities. We apply our theory to the (1/4)-filled band quasi-one-dimensional organic charge-transfer solids, in general, and to 2:1 tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenafulvalene cationic salts, in particular. We believe that many recent experiments strongly indicate the Wigner crystal to bond-charge-density Wave transition in several members of the TMTTF family. We explain the occurrence of two different antiferromagnetic phases but a single spin-Peierls state in the generic phase diagram for the 2:1 cationic solids. The antiferromagnetic phases can have either the Wigner crystal or the bond-charge-spin-density wave charge occupancies. The spin-Peierls state is always a bond-charge-density wave. Note: Link is to the article in a subscription database available to users affiliated with Butler University. Appropriate login information will be required for access. Users not affiliated with Butler University should contact their local librarian for assistance in locating a copy of this article. Rahul Hardikar