The University of Queensland

Centre for Mathematical Physics

SEMINAR

Speaker:        Professor Rajiv Singh, Department of Physics,

   University of California

Title:            Spectra of Quantum Antiferromagnets

10.30am, Wednesday 23rd November, 2005

Priestley  Blding, room 641

Abstract:

Understanding strongly correlated many-body systems that

do not appear to fit into the conventional quasi-particle framework 

remains a challenge. We discuss a newly developed series expansion 

method to study the single-particle and multi-particle excitation 

spectra of Quantum Antiferromagnets. When applied to the Alternating

Heisenberg Chain, one obtains a very rich two-particle spectra 

with multiple bound (and antibound) states outside the continuum. The 

model allows one to study the crossover from a quasi-particle dominated

Neutron Scattering spectra to one where the spectral weight has completely

shifted into the many-particle continuum. We discuss extensions of these

studies to two dimensions.

All interested are invited to attend.  The group also meets for lunch approx 1.15pm at the staff club each Wednesday.

 

Enquiries to Katrina Hibberd email: keh@maths.uq.edu.au