Tsing Hua Univ, Ctr Adv Study, Beijing 100084, Peoples R China; Int Ctr Theoret Phys, I-34100 Trieste, Italy; Acad Sinica, Inst Theoret Phys, Beijing 100080, Peoples R China
英文摘要:
A simplified version of the symmetric Kondo lattice model, the Kondo necklace model, is studied by using a representation of impurity and conduction electron spins in terms of local Kondo singlet and triplet operators. Within a mean-field theory, a spin gap always appears in the spin triplet excitation spectrum in one dimension (1D), leading to a Kondo spin liquid state for any finite values of coupling strength t/J (with t as hopping and J as exchange); in 2D and 3D cubic lattices the spin gaps are found to Vanish continuously around (t/J)(c)approximate to 0.70 and (t/J)(c)approximate to 0.38, respectively, where quantum phase transitions occur and the Kondo spin liquid state changes into an antiferromagnetically long-range ordered state. These results are in agreement with variational Monte Carlo, higher-order series expansion, and recent quantum Monte Carlo calculations for the symmetric Kondo lattice model.
Zhang, GM,Gu, Q,Yu, L. Kondo spin liquid and magnetically long-range ordered states in the Kondo necklace model[J]. PHYSICAL REVIEW B,2000,62(1):69-72.
