A current of electrons traversing a landscape of localized spins possessing non-coplanar magnetic order gains a geometrical (Berry) phase which can lead to a Hall voltage independent of the spin-orbit coupling within the material--a geometrical Hall effect. We show that the highly-correlated metal UCu5 possesses an unusually large controllable geometrical Hall effect at T<1.2K due to its frustration-induced magnetic order. The magnitude of the Hall response exceeds 20% of the \nu=1 quantum Hall effect per atomic layer, which translates into an effective magnetic field of several hundred Tesla acting on the electrons. The existence of such a large geometric Hall response in UCu5 opens a new field of inquiry into the importance of the role of frustration in highly-correlated electron materials.
@article{arxiv.1209.6024,
title = {Controllable chirality-induced geometrical Hall effect in a frustrated highly-correlated metal},
author = {B. G. Ueland and C. F. Miclea and Yasuyuki Kato and O. Ayala-Valenzuela and R. D. McDonald and R. Okazaki and P. H. Tobash and M. A. Torrez and F. Ronning and R. Movshovich and Z. Fisk and E. D. Bauer and Ivar Martin and J. D. Thompson},
journal= {arXiv preprint arXiv:1209.6024},
year = {2012}
}