Nonlinear conduction in charge-ordered Pr_0.63Ca_0.37MnO₃: Effect of magnetic fields

Nonlinear conduction in a single crystal of charge-ordered Pr_0.63Ca_0.37MnO₃ has been investigated in an applied magnetic field. In zero field, the nonlinear conduction, which starts at T<T_CO, can give rise to a region of negative differential resistance (NDR) which shows up below the Néel temperature. Application of a magnetic field inhibits the appearance of NDR and makes the nonlinear conduction strongly hysteritic on cycling of the bias current. This is most severe in the temperature range where the charge-ordered state melts in an applied magnetic field. Our experiment strongly suggests that application of a magnetic field in the charge-ordering regime causes a coexistence of two phases.