Neel to spin-Peierls transition in the ground and excited state of a quasi-1D Heisenberg model coupled to bond phonons.

• Main Author: Pillay, Jason Cornelius.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Science::Physics
• Online Access: http://hdl.handle.net/10356/49063
• Institution: Nanyang Technological University

The spin-Peierls transtion in the ground state (quantum phase transition) and excited state(thermal phase transition) of a quasi-1D Heisenberg model is investigated using the stochastic series expansion quantum monte carlo method. The transition from a gapless Neel state to a spin-gapped Peierls state is studied in the parameter space spanned by spatial anisotropy, inter-chain coupling and spin-lattice coupling. It is found that for any inter-chain coupling, the transition to a dimerized Peierls state only occurs when the spin-lattice coupling exceeds a finite, non-zero critical value.