Diagonal ladders: A class of models for strongly coupled electron systems

Article

关键词: T-J MODEL;    MATRIX RENORMALIZATION-GROUP;    2-DIMENSIONAL HUBBARD-MODEL;    LOW-TEMPERATURE PROPERTIES;    QUANTUM SPIN LADDERS;    STRIPED PHASE;    HARTREE-FOCK;    DOMAIN-WALLS;    ANTIFERROMAGNETS;    MAGNETISM;   

DOI  :  10.1103/PhysRevB.59.7973

来源: SCIE

【 摘 要 】

We introduce a class of models defined on ladders with a diagonal structure generated by n(p) plaquettes. The case n(p)= 1 corresponds to the necklace ladder and has remarkable properties that are studied using density matrix renormalization-group and recurrent variational ansatzes. The antiferromagnetic Heisenberg (AFH) model on this ladder is equivalent to the alternating spin-l/spin-1/2 AFH chain, which is known to have a ferromagnetic ground state (GS). For doping 1/3 the GS is a fully doped (1,1) stripe with the holes located mostly along the principal diagonal while the minor diagonals are occupied by spin singlets. This stare can be seen as a Mott insulator of localized Cooper pairs on the plaquettes. A physical picture of our results is provided by a t(p)-J(p)-t(d) model of plaquettes coupled diagonally with a hopping parameter td. In the limit t(d) --> infinity we recover the original t-J model on the necklace ladder while for a weak hopping parameter the model is easily solvable. The GS in the strong hopping regime is essentially an on link'' Gutzwiller projection of the weak hopping GS. We generalize the t(p)-J(p)-t(d) model to diagonal ladders with n(p)>l and the two-dimensional square lattice. We use in our construction concepts familiar in statistical mechanics such as medial graphs and Bratelli diagrams. [S0163-1829(99)05108-5].

【 授权许可】

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