Edge excitations in quantum spin chains

Tai Kai Ng, SJ Qin, Zb Su

Tomasz Wydro, McCabe, John F.

This paper studies the Yang-Lee edge singularity of 2-dimensional 2D Ising model through a quantum spin chain. In particular, finite-size scaling measurements on the quantum spin chain are used to determine the low-lying excitation spectrum and central charge at the Yang-Lee edge singularity. The measured values are consistent with predictions for the (A4, A1) minimal conformal field theory.

Jizhong Lou, Changfeng Chen, Xiaoqun Wang

A recent study [J. Lou, et al., Phys. Rev. Lett. 94, 217207 (2005)] reveals that topological edge effects induce bound midgap states in antiferromagnetic Heisenberg chains with a staggered magnetic field. We report density matrix renormalization group calculations that examine the effects of high magnetic field on the gap and midgap states and the range of validity of the field theory prediction on their scaling behavior. We also investigate the effects of the site parity (i.e., even or odd number of sites in the chain), the dilution of the spin chain by dopant atoms, and the uniform magnetic field on the emergence and evolution of the midgap states. The results provide useful insights into the behavior of the edge excitations in spin chain materials, which should facilitate the comparison between theory and experiment and stimulate further investigations.

Vladyslav O. Cheranovskii

JOHN F. MCCABE, Tomasz Wydro

This paper studies the Yang–Lee edge singularity of 2-dimensional (2D) Ising model through a quantum spin chain. In particular, finite-size scaling measurements on the quantum spin chain are used to determine the low-lying excitation spectrum and central charge at the Yang–Lee edge singularity. The measured values are consistent with predictions for the (A4, A1) minimal conformal field theory.

Jill C. Bonner, John B. Parkinson