45 research outputs found
Transport and Magnetic Studies of New Mixed-Valence Compounds: K3Cu8Se6, KCu3Se2, K3Cu8Te6 and BaCuS3-x
New mixed-valent copper chalcogenides BaCuS3_x and K3Cu8X6 with X = Se or Te and KCu3Se2, with chemical patterns corresponding to the recently investigated K3Cu8S6 and KCu3S2, were synthesized. For these new samples the results of resistivity and magnetic susceptibility measurements are presented. For BaCuS3_x, K3Cu8Se6 and KCu3Se2 the metal—insulator transition is observed with the low temperature phase being metallic, which is untypical, whereas K3Cu8Te6 is a metal in the investigated temperature range. The temperature dependence of magnetic susceptibility of the studied samples testifies to their diamagnetic or weakly paramagnetic behaviour
Evidence of phonon-assisted tunnelling in electrical conduction through DNA molecules
We propose a phonon-assisted tunnelling model for explanation of conductivity
dependence on temperature and temperature-dependent I-V characteristics in
deoxyribonucleic acid (DNA) molecules. The capability of this model for
explanation of conductivity peculiarities in DNA is illustrated by comparison
of the temperature dependent I-V data extracted from some articles with
tunnelling rate dependences on temperature and field strength computed
according to the phonon-assisted tunnelling theory.
PACS Codes: 87.15.-v, 71.38.-k, 73.40.GkComment: 6 pages, 3 figure
Superconductivity, Charge Density Wave and Charge Kondo States in Systems of Coexisting Itinerant Electrons and Local Pairs
The properties of a system of coexisting local pairs and itinerant electrons described by the (hard-core) boson-fermion model are discussed. For the first time we include into analysis of the model not only the superconducting and non-ordered (normal) states but also the charge density wave phases as well as the so-called charge Kondo state. Within an extended mean-field approximation, a mutual stability of charge density wave, superconducting and charge Kondo states are determined at T = 0 in the case of half-filled fermionic and bosonic bands
Transport and Magnetic Studies of New Mixed-Valence Compounds: KCuSe, KCuSe, KCuTe and BaCuS
New mixed-valent copper chalcogenides BaCuS and KCuX with X=Se or Te and KCuSe, with chemical patterns corresponding to the recently investigated KCuS and KCuS, were synthesized. For these new samples the results of resistivity and magnetic susceptibility measurements are presented. For BaCuS, KCuSe and KCuSe the metal-insulator transition is observed with the low temperature phase being metallic, which is untypical, whereas KCuTe is a metal in the investigated temperature range. The temperature dependence of magnetic susceptibility of the studied samples testifies to their diamagnetic or weakly paramagnetic behaviour