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The conduction relaxations of polycrystalline La0.5Ca0.5Mn0.95Fe0.05O3 upon imposing rectangle electric current pulses (with minute time scale) are studied in details. We observe clear “overshooting” features of the conduction relaxation at both the front and rear edges of the current pulse so long as the pulse is sufficiently high. The Joule heating effect and the intrinsic stabilization of the ferromagnetic metal phase by the current pulse are linked in understanding our observations, and these effects may be applicable for resistance switching function. [ABSTRACT FROM AUTHOR]

Measurements of the dynamical electrical transport behavior are performed on electron-doped manganites LaCa(MnRu)O ( x=0 and 0.02). An undoped sample possesses a robust charge-ordered antiferromagnetic ground state, and only a positive resistivity relaxation can be observed. However, a low-temperature negative relaxation behavior arises after inducing a few ferromagnetic orders to the charge-ordered matrix by tiny Ru doping. We assigned this difference to the dynamical competition between ferromagnetic metallic and charge-ordered insulating phases. Consistently, for a doped sample, the crossover from positive to negative resistivity relaxation behavior ensues around T=115 K, which is just below the ferromagnetic Curie temperature. [ABSTRACT FROM AUTHOR]

The conduction relaxations of polycrystalline La0.5Ca0.5Mn0.95Fe0.05O3 upon imposing rectangle electric current pulses (with minute time scale) are studied in details. We observe clear “overshooting” features of the conduction relaxation at both the front and rear edges of the current pulse so long as the pulse is sufficiently high. The Joule heating effect and the intrinsic stabilization of the ferromagnetic metal phase by the current pulse are linked in understanding our observations, and these effects may be applicable for resistance switching function. [ABSTRACT FROM AUTHOR]