Numerical Study of the Spin-1 Antiferromagnetic Heisenberg Chain with a Spin-1/2 Impurity

Abstract

Low-lying excited states as well as the ground state of the spin-1 antiferromagnetic Heisenberg chain with a spin-1/2 impurity are studied by means of a method of numerical diagonalization. The isotropic nearest-neighbor exchange coupling plus the uniaxial single-ion-type anisotropy energy is assumed for the host-system Hamiltonian. The energy differences between the ground state and the low-lying excited states, which appear in the Haldane gap, are estimated in the thermodynamic limit. The results are used to analyze the electron-spin-resonance experimental data on Ni(C${}_2$H${}_8$N${}_2$)${}_2$NO${}_2$(ClO${}_4$), abbreviated NENP, containing a small amount of spin-1/2 Cu${}^{2+}$ impurities. It is found that in this system, the impurity-host $($Cu${}^{2+}$-Ni${}^{2+}$$)$ coupling is ferromagnetic and its magnitude is about 5\% of the magnitude of the host-host $($Ni${}^{2+}$-Ni${}^{2+}$$)$ coupling.

18 pages, plain TeX with 4 tables(gzipped and uuencoded), 9 figures available upon request from [email protected], to be published in J. Phys. Soc. Jpn., Vol.64, No.10 (Oct. 1995)

References in corpus (4)

• Finite-lattice extrapolations for a Haldane gap antiferromagnet
• Impurities in $s=1$ Heisenberg Antiferromagnets
• Impurity-Bond Effect on the Spin-1 Antiferromagnetic Heisenberg Chain
• Effect of a Spin-1/2 Impurity on the Spin-1 Antiferromagnetic Heisenberg Chain

Cited by in corpus (3)

• Comparison of S=0 and S=1/2 Impurities in Haldane Chain Compound, $Y_{2}BaNi{O}_5$
• Effects of edges in spin-1/2 bond-alternating Heisenberg chains: Matrix-product variational approach
• Effect of the hole doping into the Haldane-gap state on the one-dimensional $S=1$ $t$-$J$ model