How to Cite
Downloads
Métricas Alternativas
Dimensions
Abstract
We prepared doped perovskite manganites of La₀.₇₇Ca₀.₂₃MnO₃ and La₀.₆₇Ba₀.₃₃MnO₃ by the solid-state reaction method. The samples were characterized electrically, magnetically, and structurally, and the effect of different preparation routines was studied. The X-ray diffraction patterns showed a cubic unit cell with parameter a varying between 3.83 and 3.90 Å. The resistivity measurements as a function of temperature showed a marked decrease when a magnetic field was switched on. All the samples displayed a transition from metallic to semiconductor behavior at temperatures Tp between 175 and 250 K; this temperature, however, becomes higher with increasing magnetic field. The typical semiconductor behavior at T > Tp can be reasonably well fitted to a non-adiabatic small polaron hopping model.
References
R. Von Helmolt, J. Wecker, B. Holzapfel, L. Schultz, and K. Samwer. Giant Negative magnetoresistance in perovskitelike La2/3Ba1/3MnO3. Phys. Rev. Lett. 71 (14), 2331-2333 (1993).
S. Jin, T. H. Tiefel, M. McCormack, R. A. Fastnacht, R. Ramesh, and L. H. Chen. Thousandfold change in resistivity in magnetoresistive La-Ca-Mn-O films. Science 264, 413-415 (1994).
A. J. Millis. Lattice effects in magnetoresistive manganese perovskites. Nature 392, 147-150 (1998).
P. Schiffer, A. P. Ramirez, W. Bao, and S. W. Cheong. Low temperature magnetoresistance and the magnetic phase diagram of La1-xCaxMnO3. Phys. Rev. Lett. 75 (18), 3336-3339 (1995).
H. L. Ju, J. Gopalakrishnan, J. L. Peng, Qi Li, G. C. Xiong, T. Venkatesan, and R. L. Greene. Dependence of giant magnetoresistance on oxygen stoichiometry and magnetization in polycrystalline La0.67Ba0.33MnO3. Phys. Rev. B 51 (9), 6143-6146 (1995).
C. Zener. Interaction between the d-shells in the transition metals. II. Ferromagnetic compounds of manganese with perovskite structure. Phys. Rev. 82 (3), 403-405 (1951).
A. J. Millis, R. Mueller, and Boris Y. Shraiman. Fermi-liquid-to-polaron crossover. II. Double exchange and the physics of colossal magnetoresistance. Phys. Rev. B 54 (8), 5405-5417 (1996).
J. M. De Teresa, M. R. Ibarra, J. Blasco, J. García, C. Marquina, P. A. Algarabel, Z. Arnold, K. Kamenev, C. Ritter and R. von Helmolt. Spontaneous behavior and magnetic field and pressure effects on La2/3Ca1/3MnO3 perovskite. Phys. Rev. B 54 (2), 1187-1193 (1996).
W. Westerburg, G. Jakob, F. Martín, and H. Adrian. High-temperature transport properties of La0.61Ca0.39MnO3 films. Journal of Magnetism and Magnetic Materials, 196-197, 536-538 (1999).
H. Y. Hwang, S-W. Cheong, P.G. Radaelli, M. Marezio, and B. Batlogg. Lattice Effects on the Magnetoresistance in Doped LaMnO3. Phys. Rev. Lett. 75 (5), 914-917 (1995).
R. Mahesh, R. Mahendiran, A. K. Raychaudhuri, and C. N. R. Rao. Effect of Particle size on the Giant Magnetoresistance of La0.61Ca0.39MnO3. Appl. Phys. Lett. 68 (16), 2291-2293 (1996).
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.