Simple transport models for the temperature-dependent linear magnetoresistance of pnictide and cuprate superconductors*

Taken in conjunction with the temperature (T) dependence of the zero-field resistivity, simple transport models invoking e.g., realistic variations in charge-carrier density are shown to be sufficient to explain the linear magnetoresistance and field-temperature resistance scaling recently observed in high-temperature pnictide and cuprate superconductors. Hence, though the T-linear zero-field resistance is a definite signature of the "strange metal" state of high-temperature superconductors, their linear magnetoresistance and its scaling need not be; instead they may merely be signatures of disorder. Straightforward experimental tests of these assertions are proposed.