Semiconducting-metallic transition of singlecrystalline ferromagnetic Hf-doped CuCr^sub 2^Se^sub 4^ spinels

Chalcogenide spinels show a variety of physical properties and are very good candidates for electronic and high-frequency applications. We report the measurements of magnetic susceptibility, magnetic isotherm, electrical conductivity, thermoelectric power and calculations of the superexchange and do...

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Bibliographic Details
Published in:Physica. B, Condensed matter Condensed matter, 2017-09, Vol.520, p.116
Main Authors: Maciazek, E, Malicka, E, Gagor, A, Stoklosa, Z, Gron, T, Sawicki, B, Duda, H, Gudwanski, A
Format: Article
Language:English
Subjects:
Chemical elements
Electrical resistivity
Ferromagnetism
Hafnium
Integrals
Magnetic fields
Magnetic moments
Magnetic permeability
Physical properties
Quantitative analysis
Semiconductors
Single crystals
Studies
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Summary:Chalcogenide spinels show a variety of physical properties and are very good candidates for electronic and high-frequency applications. We report the measurements of magnetic susceptibility, magnetic isotherm, electrical conductivity, thermoelectric power and calculations of the superexchange and double-exchange integrals made for singlecrystalline Cu[CrxHfx)Se4 spinels. The results showed a ferromagnetic order of magnetic moments below the Curie temperatures of 390 K and, an increase in the splitting of the zero-field cooled and field cooled susceptibilities with increasing Hf-content below the room temperature suggesting a slight spin-frustration and a rapid transition from semiconducting to metallic state at room temperature. A quantitative evaluation of the exchange Hamiltonian showed that the total hopping integral rapidly decreased and the bandwidth of the 3d t2g band due to Cr3+ and Cr4+ ions strongly narrowed from 0.76eV for y = 0 to 0.28 eV for y = 0.14. The narrowing of this band appears to be responsible for semiconducting properties of the Hf-doped CuCr2Se4 spinels below the room temperature.
ISSN:0921-4526
1873-2135