Impedance spectroscopy evidence of the phase separation in La{sub 0.3}Pr{sub 0.4}Ca{sub 0.3}MnO{sub 3} manganite
We have measured electrical resistance R(T), magnetization M(T), and for the first time impedance spectroscopy Z(T,{omega}) of polycrystalline samples of La{sub 0.3}Pr{sub 0.4}Ca{sub 0.3}MnO{sub 3} compounds. The combined results suggest the coexistence of two metallic ferromagnetic phases below the Curie temperature of the system. The R(T) data exhibit two important features: the occurrence of a metal{endash}insulator (MI) transition at temperatures close to T{sub MI}{approximately}170K and a large thermal hysteresis below T{sub MI}. The first feature was found to be associated with the development of ferromagnetism and takes place when the magnetization of the samples becomes about 15% of its saturated value at low temperatures. The second feature suggests two contributions to R(T) below the Curie temperature T{sub C}. The Z(T,{omega}) data taken from 77 to 300 K and frequency varying from 5 to 10{sup 7}Hz are much more valuable. These results reveal two well defined bulk contributions to the transport properties of these manganites below {similar_to}170 K: one occurring at high frequencies {similar_to}4{times}10{sup 6}Hz and a second one at low frequencies, typically on the order of 1.5{times}10{sup 5}Hz. An analysis of the Z(T,{omega}) data suggests that these contributions are related to the spin lattice relaxation rate of the two distinct phases. Such a result suggests a phase separation below T{sub C} in the compound in complete agreement with recent muon spin relaxation and neutron spin echo measurements performed on manganites. {copyright} 2001 American Institute of Physics.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40203823
- Journal Information:
- Journal of Applied Physics, Vol. 89, Issue 11; Other Information: DOI: 10.1063/1.1357139; Othernumber: JAPIAU000089000011006636000001; 291111MMM; PBD: 1 Jun 2001; ISSN 0021-8979
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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