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Effect of the A-site randomness on magnetotransport properties of PrBaMn2O6 manganites.

Sergei Trukhanov 1Igor Troyanchuk 1Aleksey Trukhanov 2Henryk Szymczak 3

1. The Institute of Solid State & Semiconductor Physics, National Academy of Science of Belarus, 17 P.Brovka, Minsk 220072, Belarus
2. Vitebsk State University (VSU), av. Moskovskaya 33, Vitebsk 210036, Belarus
3. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland


A-site ordered manganites of the PrBaMn2O6 system have been obtained using a two-step synthesis and characterized with respect to the chemical composition, crystal structure, magnetic and magnetotransport properties. The physical properties of the A-site ordered PrBaMn2O6 manganites obtained using this method significantly differ from the properties of A-site disordered Pr0.50Ba0.50MnO3 synthesized by means of the conventional ceramic technology and depend on the degree of ordering of the Pr3+ and Ba2+ cations. In particular, the A-site disordered Pr0.50Ba0.50MnO3 has a cubic perovskite-like unit cell, while A-site ordered PrBaMn2O6 has a tetragonal unit cell. Cation states in the system under study are reversible. The A-site ordered PrBaMn2O6 state remains stable upon heating in an oxidizing medium up to 1300 0C. The ordering of the Pr3+ and Ba2+ cations leads to a significant increase in the critical temperatures of phase transitions. In particular, PrBaMn2O6 with the maximum degree of ordering is a metallic ferromagnet with the Curie temperature TC ~ 320 K, whereas TC of a fully disordered sample is on the order of 140 K. The samples with intermediate degrees of ordering contain two magnetic phases. Slightly below TC, all such samples exhibit a metal-insulator transition and a peak of the magnetoresistance, which amounts to approximately 10 and 65 % in a magnetic field of 9 kOe for the fully ordered PrBaMn2O6 and disordered Pr0.50Ba0.50MnO3 , respectively. The results are interpreted in terms of the Goodenough-Kanamori empirical rules for indirect exchange interactions with allowance for the degree of ordering of the Pr3+ and Ba2+ cations.


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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium C, by Sergei Trukhanov
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-12 12:43
Revised:   2009-06-07 00:44