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NEW SEMICONDUCTOR SPIN-GLASS CU2/3GE1/3CR2S4 - COMPARISON OF MAGNETIC AND ELECTRIC PROPERTIES OF THE SPIN-GLASSES CU0.5IN0.5CR2SE4 AND CU2/3GE1/3CR2S4статья
Информация о цитировании статьи получена из
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Web of Science
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: KOROLEVA LI, VIROVETS TV, ABRAMOVICH AI, KESSLER YA
- Журнал: Journal of Magnetism and Magnetic Materials
- Том: 115
- Номер: 2-3
- Год издания: 1992
- Издательство: Elsevier BV
- Местоположение издательства: Netherlands
- Первая страница: 311
- Последняя страница: 323
- DOI: 10.1016/0304-8853(92)90074-X
- Аннотация: The magnetic and electric properties of a new semiconductor compound Cu2/3Ge1/3Cr2S4 have been studied. The data of the X-ray diffraction analysis and IR spectra show that this compound possesses a spinel-like structure with a crystallographic ordering of 1:1-type between the Cu1+ and Ge4+ ions in a tetrahedral sublattice. This compound has magnetic properties typical of spin glasses (SGs): a maximum initial susceptibility at a certain temperature, a dependence of low-temperature magnetic properties on the thermomagnetic history of the sample and the absence of spontaneous magnetization, the latter shown by the Belov-Arrot method. The critical behaviour has been studied by means of the nonlinear susceptibility chi(nl) in the region of the freezing temperature T(f), which is defined as the temperature of the maximum of the chi(nl)(T) curve. The critical exponents have been determined: gamma = 3.9 +/- 0.1, delta = 4.8 +/- 0.1, beta = 1 +/- 0.2. The experimental points satisfactorily fit the scaling function g(X) in the critical field range H less-than-or-equal-to 50 Oe and for normalized temperatures t = T - T(f)/T(f) < 0.5. The freezing temperature T(f)' determined from the maximum initial susceptibility in an ac field, depends on the measurement frequency according to the Vogel-Fulcher law, the constant T0 in this law being close to T(f). The dependence of T(f)' on the static magnetic field H for both the compound Cu2/3Ge1/3Cr2S4 and the previously studied Cu0.5In0.5Cr2Se4 obeys the relation of Almeida-Thouless. A giant negative magnetoresistance (MR), approaching 80% in a field of 30 kOe, has been found in the semiconductor SGs Cu2/3Ge1/3Cr2S4 and Cu0.5In0.5Cr2Se4. A minimum is observed in the temperature dependence of the MR at T(f). These experimental facts indicate that in the SGs inder investigation a phase transition SG-paramagnetism takes place. The nature of the SG state is discussed.
- Добавил в систему: Абрамович Анна Ивановна