Even after decades of research on the high-Tc cuprates, several parts of their phase diagrams remain mysterious, especially the normal state above Tc near optimal doping, a region commonly referred to as the strange metal phase. New avenues for studying this physics were opened up by the discovery of the iron-based high-Tc materials, which also exhibit strange metal characteristics, particularly a T-linear resistivity and a roughly 1/T Hall coefficient near optimal doping. In this talk I will present measurements of the Hall coefficient in phosphorous-doped BaFe2As2 in fields of up to 65 tesla, which is enough to suppress superconductivity even at optimal doping. These measurements reveal a striking parallel between the effects of increasing magnetic field and the effects of increasing temperature, a phenomenon that is reminiscent of the field-temperature scaling seen in the resistivity of this compound. This characteristic field dependence allows us to clearly identify the extent of strange metal physics in the entire phosphorous-doping phase diagram. Intriguingly, the presence of strange metal behavior in the Hall coefficient is directly related to the presence of the superconductivity across the phase diagram. I will discuss the implications of these observations for different approaches to the strange metal as well as the opportunities they present for future research.
