Magnetization and magnetoresistive response of {LiMn_2O_4} near the charge ordering transition

We report magnetization and magnetoresistance studies of the geometrically frustrated spinel compound {LiMn_2O_4} near its charge ordering temperature. The effect of a 7 T magnetic field is to very slightly shift the transition in the resistivity to lower temperatures resulting in large negative magnetoresistance with significant hysteresis. This hysteresis is not reflected in the magnetization. These observations are compared with what is found in the colossal magnetoresistance and charge ordering perovskite manganese oxides. The manner in which geometric frustration influences the coupling of charge and spin degrees of freedom is examine