Y. Yamato

Current-induced nonlinear conduction of two-electron doped manganites Ca1-xCexMnO3

We have investigated the current-induced nonlinear conduction in a charge-ordered phase of two-electron doped manganites Ca1−xCexMnO3 (x = 0.1 and 0.167). The substitution of Ce4+ ion for Ca2+site of the parent matrix causes two-electron doping with the chemical formula . Seebeck coefficient data of Ca0.9Ce0.1MnO3 are, in both its temperature dependence and its magnitude, very similar to those of Ca0.8Sm0.2MnO3, leading to further evidence for two-electron doping. The VI characteristics measured using a long pulsed current show a negative differential resistance and its associated giant electroresistance effect. It is demonstrated that a temperature rise across the samples due to Joule heating is not responsible for a huge decrease in resistance observed here.

Colossal electroresistance and colossal magnetoresistive step in paramagnetic insulating phase of single crystalline bilayered manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7

in paramagnetic insulating phase of single crystalline bilayered manganite „La0.4Pr0.6...1.2Sr1.8Mn2O7 Y. Yamato, M. Matsukawa, Y. Murano, R. Suryanarayanan, S. Nimori, M. Apostu, A. Revcolevschi, K. Koyama, and N. Kobayashi Department of Materials Science and Engineering, Iwate University, Morioka 020-8551, Japan Laboratoire de Physico-Chimie de L’Etat Solide, CNRS, UMR8182, Universite Paris-Sud, 91405 Orsay, France National Institute for Materials Science, Tsukuba 305-0047, Japan Department of Physical, Theoretical and Materials Chemistry, Faculty of Chemistry, Al. I. Cuza University, Carol I, 700506 Iasi, Romania Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

Steplike lattice deformation of single crystalline (La0.4Pr0.6)1.2Sr1.8Mn2O7 bilayered manganite.

We report a steplike lattice transformation of single crystalline (La0.4Pr0.6)1.2Sr1.8Mn2O7 bilayered manganite accompanied by both magnetization and magnetoresistive jumps, and examine the ultrasharp nature of the field-induced first-order transition from a paramagnetic insulator to a ferromagnetic metal phase accompanied by a huge decrease in resistance. Our findings support that the abrupt magnetostriction is closely related to an orbital frustration existing in the inhomogeneous paramagnetic insulating phase rather than a martensitic scenario between competing two phases.

Anomalous pressure effect on steplike magnetostriction of (La0.4Pr0.6)1.2 Sr1.8Mn2O7 bilayered manganese oxide

We report the pressure effect on a steplike magnetostriction of single crystalline (La0.4 Pr0.6)1.2Sr1.8Mn2O7 bilayered manganite, for our understandings of the ultrasharp nature of the field-induced first-order transition from a paramagnetic insulator to a ferromagnetic metal phase. Application of pressure suppresses a steplike transformation and causes a broad change in the magnetostriction. A delocalization of carriers is promoted with the applied pressure, resulting in the suppressed steplike behavior. The steplike behavior observed is closely related to the existence of localized carriers.

Effect of pressure on lattice distortion, transport and magnetic properties of Pr-substituted La(1.2)Sr(1.8)Mn(2)O(7) bilayered manganite.

We have studied the effect of pressure on the anomalous lattice striction, both in the ab-plane and along the c-axis, of (La,Pr)(1.2)Sr(1.8)Mn(2)O(7) single crystals over the temperature region where the paramagnetic insulator to ferromagnetic metal transition takes place. We have examined the temperature dependence of the resistivity and the magnetization under applied pressure. The chemical pressure effect due to Pr-substitution at the La site suppresses the transition temperature of the parent crystal, while the application of external pressure on Pr-substituted crystals enhances the double exchange driven metallic state, resulting in a stable rise of T(c).