We report on a comprehensive optical, transport and thermodynamic study of the Zintl compound Yb14MnSb11, demonstrating that it is the first ferromagnetic Kondo lattice compound in the underscreened limit. We propose a scenerio whereby the combination of Kondo and Jahn-Teller effects provides a consistent explanation of both transport and optical data.
@article{arxiv.cond-mat/0507693,
title = {Optical study of interactions in a d-electron Kondo lattice with ferromagnetism},
author = {K. S. Burch and A. Schafgans and N. P. Butch and T. A. Sayles and M. B. Maple and B. C. Sales and D. Mandrus and D. N. Basov},
journal= {arXiv preprint arXiv:cond-mat/0507693},
year = {2007}
}