Abstract:
TiOBr belongs to a select group of quasi-one-dimensional quantum
materials which undergo a spin-Peierls phase transition. Driven by a
combination of antiferromagnetic interactions and strong magnetoelastic
coupling, these compounds develop a dimerized singlet ground state at
low temperatures. However, unlike conventional spin-Peierls compounds
such as CuGeO3, TiOBr appears to differ from the standard spin-Peierls
model in several important respects. In particular, TiOBr has been
shown to exhibit not one, but two successive phase transitions upon
cooling, displaying both commensurate and incommensurate spin-Peierls
ground states. In this talk I will discuss the results of recent x-ray
and neutron scattering measurements on single crystal and powder
samples of TiOBr. I will describe how these measurements can provide
insight into the nature of the low temperature phase diagram, critical
behaviour, and magnetic excitation spectrum of this unusual material.