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Volume 6 Research & Reviews: Journal of Material Sciences
ISSN: 2321-6212 Magnetic Materials 2018
October 22-23, 2018
October 22-23, 2018 | Rome, Italy
3rd International Conference on
Magnetism and Magnetic Materials
Critical behavior of GaMnAs diluted magnetic semiconductors near the Curie temperature
Shavkat U Yuldashev
Dongguk University, South Korea
GaMnAs have been studied intensely over the last few decades and have become a model system for diluted ferromagnetic
semiconductors. At present, it is accepted that the Curie temperature of GaMnAs with metallic type of the conductivity
coincides well with the maximum of the temperature derivative of the resistivity dρ/dT, similar to the ferromagnetic metals
like Ni and Fe, whereas, for samples with low concentration of free carriers, the TC coincides with the resistivity maximum. The
critical behavior of GaMnAs near the Curie temperature was experimentally studied by using the temperature dependencies of
the resistivity, the specific heat, and the magnetization of GaMnAs. It is shown that the determination of TC from the maximum
of the temperature derivative of the resistivity is valid only for the samples with a high concentration of free carriers. For the
samples with low concentration of free carriers, the TC coincides with the resistivity maximum. The magnetic specific heat for
T > TC demonstrates the crossover from the one dimensional to the three dimensional critical behavior when temperature
become closer to the Curie temperature. This is explained by the existence of Mn-Mn dimers oriented along one direction at
the beginning of the formation of the ferromagnetic phase on the paramagnetic side of the phase transition.
Figure 1: Temperature dependencies of the resistivity for the GaMnAs with 8% of Mn, annealed at low temperature. Inset shows the enlarged picture of the
resistivity behavior near the maximum and the magnetic specific heat, respectively.
Recent Publications
1. Z A Yunusov, Sh U Yuldashev, Y H Kwon, D Y Kim, S J Lee, et al. (2018) Band gap engineering of ZnMnO diluted
magnetic semiconductor by alloying with ZnS: Journal of Magnetism and Magnetic Materials 446:206–209.
2. Sh U Yuldashev, Z A Yunusov, Y H Kwon, S H Lee, R Ahuja, et al. (2017) Critical behavior of the resistivity of GaMnAs
near the Curie temperature: Solid State Communications 263:38-41.
3. Sh U Yuldashev, V Sh Yalishev, Z A Yunusov, Y H Kwon and TWKang (2016) Magnetic phase transitions in ZnO doped
by transition metals: Physica Status Solidi C 13: 559–563.
4. Sh U Yuldashev, V Sh Yalishev, Z A Yunusov, S J Lee, H C Jeon, et al. (2015) Magnetoelectric effect in GaMnAs /P(VDF-
TrFE) composite multiferroic nanostructures: Current Applied Physics 15:S22–S25.
5. Sh U Yuldashev, Kh T Igamberdiev, Y H Kwon, S H Lee, X Liu, et al. (2012) Crossover critical behavior of Cd1-xMnxAs:
Phys. Rev. B 85: 125202:1–5.
Biography
Shavkat U Yuldashev has completed his PhD in the year 1983 from A.F. Ioffe Institute, Saint-Petersburg. He is the Professor at the Department of Physics of Dongguk
University, Seoul, South Korea. He has published more than 175 papers in reputed journals. His expertise is in diluted magnetic semiconductors and spintronics.
Shavkat U Yuldashev, Res. Rev. J Mat. Sci. 2018, Volume 6
DOI: 10.4172/2321-6212-C6-029