Anisotropic Hall effect in single crystal heavy fermion YbAgGe

Temperature- and field-dependent Hall effect measurements (down to T = 50 mK and up to H = 18 T ) are reported for YbAgGe, a heavy fermion compound exhibiting a field-induced quantum phase transition. 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. Distinct features in the anisotropic field-dependent Hall resistivity sharpen on cooling down and at the base temperature are close to the respective critical fields for the field-induced quantum critical point. At low-temperatures, the functional form of the field-dependent Hall coefficient is field-direction-dependent and complex beyond simple existing models, thus reflecting the multi-component Fermi surface of the material and its non-trivial modification at the quantum critical point.