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Pressure and magnetic field effects on transport properties of ceramic and film samples (La0.7Ca0.3)1-xMn1+xO3

Vladimir I. Mikhaylov 1Vladimir P. Dyakonov 1Valery A. Shtaba 1Eduard E. Zubov 1Oleksiy V. Pashchenko 1Andrzej Szewczyk Kazimir Piotrowski 2Henryk Szymczak 

1. National Academy of Sciences of Ukraine, Donetsk Technical-Physical Institute, R. Luxemburg 72, Donetsk 83114, Ukraine
2. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland


Many physical characteristics including the Curie temperature TC, the metal-insulator transition temperature TMI, and resistance in doped lantanum perovskite manganites - materials having "colossal" magnetoresistance (CMR) can be changed to a considerable extent by internal chemical as well as by external physical pressure. The pressure and magnetic field effects on transport and magnetoresistance effect (MRE) have been studied in both the epitaxial films and ceramics of manganites with excess manganese (La0.7Ca0.3)1-xMn1+xO3 (x = 0 - 0.2). A comparison of electrical behaviour in both kinds of ceramic and film samples of similar composition under the influence of hydrostatic pressure (up to 2 GPa) and magnetic field (up to 8 kOe) has been performed. The pressure as well as magnetic field decreases the resistivity in the region of the metal-insulator transition and shifts TMI to higher temperatures. TMI and MRE are shown to increase with increasing manganese content.
Experimental data show that the pressure and magnetic field effects on temperatures of both metal-insulator transition (TMI) and MRE peak (TMR) are considerably stronger in the films than in the ceramic samples. The linear increase of TMI and TMR by pressure was observed up to 2 GPa, and the pressure effect is stronger in the films. The main origin of the pressure-magnetic field effects is related to increasing double exchange (DE) interaction because of both the decrease of the unit cell volume and lattice distortions. The differences in the values of pressure effect on resistivity, MRE and metal-insulator transition temperatures in ceramics and in the films of the same content are due to a difference of both the oxygen nonstoichiometry and the film strain induced by lattice mismatch between the film and the substrate.


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Presentation: poster at E-MRS Fall Meeting 2003, Symposium D, by Vladimir I. Mikhaylov
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-15 12:13
Revised:   2009-06-08 12:55