From next generation gas turbines to scavenging waste heat from car exhausts, finding new materials with ultra-low thermal conductivity (κ) has the potential to lead to large gains in device efficiency. Crystal structures with inherently low κ are consequently desirable, but candidate materials are rare and often difficult to make. Using first principles calculations and inelastic neutron scattering we have studied the pyrochlore La2Zr2O7 which has been proposed as a next generation thermal barrier. We find that there is a highly anharmonic, approximately flat, vibrational mode associated with the kagome planes. Our results suggest that this mode is responsible for the low thermal conductivity observed in the pyrochlores and that kagome compounds will be a fruitful place to search for other low κ materials.
@article{arxiv.1809.06265,
title = {Kagome modes, a new route to ultralow thermal conductivity?},
author = {D. J. Voneshen and M. Ciomaga Hatnean and T. G. Perring and H. C. Walker and K. Refson and G. Balakrishnan and J. P. Goff},
journal= {arXiv preprint arXiv:1809.06265},
year = {2019}
}