Peculiarities of magnetic, galvanomagnetic, elastic, and magnetoelastic properties of EU0.55Sr0.45MnO3статья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Magnetic, elastic, magnetoelastic, transport, and magnetotransport properties of the Eu0.55Sr0.45MnO3 ceramics have been studied. A break was detected in the temperature dependence of electrical resistivity rho(T) near the temperature of the magnetic phase transformation (41 K), with the material remaining an insulator down to the lowest measurement temperature reached (rho = 10(6) Omega cm at 4.2 K). In the interval 4.2 less than or equal to T less than or equal to 50 K, the isotherms of the magnetization, volume magnetostriction, and rho were observed to undergo jumps at the critical field H-C1, which decreases with increasing T For 50 less than or equal to T less than or equal to 120 K, the jumps in the above curves persist, but the pattern of the curves changes and H-C1 grows with increasing T. The magnetoresistance Deltarho/rho = (rho(H) - rho(H) (=) (0))/rho(H) is positive for H < H-C1 and passes through a maximum at 41 K, where &UDelta;ρ/ρ = 6%. For H > H-C1, the magnetoresistance is negative, passes through a minimum near 41 K, and reaches a colossal value of 3 x 10(5) % at H = 45 kOe. The volume magnetostriction is negative and attains a giant value of 4.5 x 10(-4) at H = 45 kOe. The observed properties are assigned to the existence of three phases in Eu0.55Sr0.45MnO3, namely, a ferromagnetic (FM) phase, in which carriers are concentrated because of the gain in s-d exchange energy, and two antiferromagnetic (AFM) phases of the A and CE types. Their fractional volumes at low temperatures were estimated to be as follows: similar to3% of the sample volume is occupied by the FM phase; similar to67%, by the CE-type AFM phase; and similar to30%, by the A-type AFM phase. (C) 2004 MAIK "Nauka/Interperiodica".