Spin Glass Behaviour and Spin-Dependent Scattering in La0.7Ca0.3Mn0.9Cr0.1Ox Perovskites
WU Bai-Mei1,2, M. Ausloos2, DU Ying-Lei3, ZHENG Wei-Hua1, LI Bo1, J. F. Fagnard4, Ph. Vanderbemden4
1Structural Research Laboratory, Department of Physics, University of Science and Technology of China, Hefei 230036
2SUPRATECS, Institut de Physique B5, Universitv de Liege, B-4000 Liege, Belgium
3Department of Astronomy and Applied Physics, University of Science and Technology of China, Hefei 230036
4SUPRATECS, Institut de Electricité, Montefiore B28, Université de Liege, B-4000 Liege, Belgium
Spin Glass Behaviour and Spin-Dependent Scattering in La0.7Ca0.3Mn0.9Cr0.1Ox Perovskites
WU Bai-Mei1,2;M. Ausloos2;DU Ying-Lei3;ZHENG Wei-Hua1;LI Bo1;J. F. Fagnard4;Ph. Vanderbemden4
1Structural Research Laboratory, Department of Physics, University of Science and Technology of China, Hefei 230036
2SUPRATECS, Institut de Physique B5, Universitv de Liege, B-4000 Liege, Belgium
3Department of Astronomy and Applied Physics, University of Science and Technology of China, Hefei 230036
4SUPRATECS, Institut de Electricité, Montefiore B28, Université de Liege, B-4000 Liege, Belgium
Abstract： The magnetic, electrical and thermal transport properties of the perovskite La0.7Ca0.3Mn0.9Cr0.1Ox have been investigated by measuring dc magnetization, ac susceptibility, the magnetoresistance and thermal conductivity in the temperature range of 5--300K. The spin glass behaviour with a spin freezing temperature of 70K has been well confirmed for this compound, which demonstrates the coexistence and competition between ferromagnetic and antiferromagnetic clusters by the introduction of Cr. Colossal magnetoresistance has been observed over the temperature range investigated. The introduction of Cr causes the ``double-bump'' feature in electrical resistivity ρ(T). Anomalies on the susceptibility and the thermal conductivity associated with the double-bumps in ρ(T) are observed simultaneously. The imaginary part of ac susceptibility shows a sharp peak at the temperature of insulating--metallic transition where the first resistivity bump was observed, but it is a deep-set valley near the temperature where the second bump in ρ(T) emerges. The thermal conductivity shows an increase below the temperature of the insulating--metallic transition, but the phonon scattering is enhanced accompanying the appearance of the second peak of double-bumps in ρ(T). We relate those observed in magnetic and transport properties of La0.7Ca0.3Mn0.9Cr0.1Ox to the spin-dependent scattering. The results reveal that the spin--phonon interaction may be of more significance than the electron (charge)--phonon interaction in the mixed perovskite system.
2005, Vol. 22 
