Density-Matrix Renormalization Group Study on an Impurity Symmetrically Coupled to a Quantum Heisenberg Chain

Abstract

We calculate the impurity susceptibility for a spin-1/2 magnetic impurity symmetrically coupled to its two nearest-neighbor spins in an antiferromagnetic Heisenberg spin-1/2 chain. This is done by extending White's density-matrix renormalization group (DMRG) technique to finite temperatures. It is found that the impurity susceptibility satisfies Curie law at low temperatures, and thatthe Curie constant decreases rapidly with increasing coupling constant between the impurity spin and the spins in the chain. For strong couplings, a logarithmic dependence of the susceptibility on temperature emerges.The Curie law behavior agrees with the DMRG analysis at zero temperature but deviates from the prediction of conformal field theory.