“Random Quantum Spin Chains with Long-Range Interactions” Stephen Haas (USC)

Wednesday, December 3, 2014 - 4:00pm
Condensed Matter Journal Club Seminars

A real-space renormalization group technique is used to study the anisotropic Heisenberg model with long-range interactions, decaying with a power α, which are generated by placing spin sites at random positions along the chain. This method permits a large-scale finite-size analysis of systems with up to 256 spins, along with a disorder average over up to 300,000 realizations. Analyzing the distribution of the first excitation energy from the ground state, we find a critical power-law decay where the  distribution function is critical, separating an insulator phase at larger α where the distribution is Poissonian, and a metallic state at smaller α, where it follows the Wigner surmise.

PAB 4-330