arXiv:1908.03450 · Physical review. B./Physical review. B
Bond particle theory for the pseudogap phase of underdoped cuprates
R. Eder
Abstract
We present a theory for the lightly doped $t\text{\ensuremath{-}}J$ model that is of possible relevance for the normal state of underdoped cuprates. Starting from an arbitrary dimer covering of the plane, an exact representation of the $t\text{\ensuremath{-}}J$ Hamiltonian in terms of bond bosons and fermions can be derived. Since all dimer coverings must give identical results for observable quantities, we construct an approximate but translationally invariant Hamiltonian by averaging the bond particle Hamiltonian over all possible dimer coverings. Treating the resulting Hamiltonian in the mean-field approximation, we find Fermi pockets centered near $(\ensuremath{\pi}/2,\ensuremath{\pi}/2)$ with a total area of $x/2$ (with $x$ the hole concentration) and a gapped spin-wave-like band of triplet excitations.