Temperature- and field-dependent Hall effect measurements are reported for YbAgGe, a heavy fermion compound exhibiting a field-induced quantum phase transition, and for two other closely related members of the RAgGe series: a non-magnetic analogue, LuAgGe and a representative, ''good local moment'', magnetic material, TmAgGe. Whereas the temperature dependent Hall coefficient of YbAgGe shows behavior similar to what has been observed in a number of heavy fermion compounds, the low temperature, field-dependent measurements reveal well defined, sudden changes with applied field; in specific for H⊥c a clear local maximum that sharpens as temperature is reduced below 2 K and that approaches a value of 45 kOe - a value that has been proposed as the T=0 quantum critical point. Similar behavior was observed for H∥c where a clear minimum in the field-dependent Hall resistivity was observed at low temperatures. Although at our base temperatures it is difficult to distinguish between the field-dependent behavior predicted for (i) diffraction off a critical spin density wave or (ii) breakdown in the composite nature of the heavy electron, for both field directions there is a distinct temperature dependence of a feature that can clearly be associated with a field-induced quantum critical point at T=0 persisting up to at least 2 K.
@article{arxiv.cond-mat/0406435,
title = {Anisotropic Hall Effect in Single Crystal Heavy Fermion YbAgGe},
author = {S. L. Bud'ko and E. Morosan and P. C. Canfield},
journal= {arXiv preprint arXiv:cond-mat/0406435},
year = {2009}
}