Electrical transport in magnetite near the Verwey transition

Kuipers, A. J. M.; Brabers, V.A.M.

doi:10.1103/physrevb.20.594

Cited by 71 publications

(49 citation statements)

References 17 publications

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“…4. 26,31 Despite some qualitative agreement with the data reported by Miyahara,22 in particular concerning the weak influence of the Ga substitution, there remain substantial differences with our numerical data that are supposed to have their origin in the nonstoichiometry of Miyahara's specimens.…”

Section: Resultscontrasting

confidence: 82%

Impurity effects upon the Verwey transition in magnetite

Brabers

Walz²,

Kronmüller³

1998

Phys. Rev. B

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110

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Magnetite single crystals Fe 3Ϫx M x O 4 doped with M ϭNi, Co, Mg, Al, Ga, and Ti were grown and annealed under a controlled atmosphere to produce homogeneous and oxygen stoichiometric samples. The cation vacancy concentration of the samples was proved to be lower than 10 Ϫ6 by means of magnetic disaccommodation spectroscopy. The Verwey temperature shift as function of the substituent concentration was determined from the temperature dependence of the resistivity. The systematics of the transition temperature shift as function of the concentration and nature of the substituents is indicative that the mechanism of the transition is related to the second-neighbor Coulomb interaction of the cations on the octahedral sites.

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Section: Resultscontrasting

confidence: 82%

Impurity effects upon the Verwey transition in magnetite

Brabers

Walz²,

Kronmüller³

1998

Phys. Rev. B

Self Cite

110

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“…A similar concept has been applied recently to explain the dynamic conductivity at the metal-insulator transition in quasi-one-dimensional ␤-Na 0.33 V 2 O 5 . 17 At low temperatures the conduction in magnetite takes place via hopping between localized states, which agrees well with both activated dc resistivity [18][19][20] and with an observed characteristic power law ϰ s ͑Ref. 21͒ of the ac conductivity.…”

Section: Introductionsupporting

confidence: 66%

Terahertz conductivity at the Verwey transition in magnetite

et al. 2005

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The complex conductivity at the (Verwey) metal-insulator transition in Fe3O4 has been investigated at THz and infrared frequencies. In the insulating state, both the dynamic conductivity and the dielectric constant reveal a power-law frequency dependence, the characteristic feature of hopping conduction of localized charge carriers. The hopping process is limited to low frequencies only, and a cutoff frequency ν1 ≃ 8 meV must be introduced for a self-consistent description. On heating through the Verwey transition the low-frequency dielectric constant abruptly decreases and becomes negative. Together with the conductivity spectra this indicates a formation of a narrow Drude-peak with a characteristic scattering rate of about 5 meV containing only a small fraction of the available charge carriers. The spectra can be explained assuming the transformation of the spectral weight from the hopping process to the free-carrier conductivity. These results support an interpretation of Verwey transition in magnetite as an insulator-semiconductor transition with structure-induced changes in activation energy.

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“…The Seebeck coefficient, S, is reported to be negative above Tv and does not depend so much on the stoichiometry [748,[757][758][759] (Fig. 5.87).…”

Section: Transport Phenomena and The Fluctuation Of Chargementioning

confidence: 94%

“…The magnitude is about -50 p.,V /Kat room temperature. Arguments have been made that log pis proportional to T-1 14, indicating variable range hopping [760], that log p is proportional to T /To rather than 1/T between Tv /2 and Tv, indicating incoherent tunneling of electrons induced by thermal motion of atoms [761], that there are electrons and holes both with thermal activation type mobility [762], or that log p is proportional to 1 /T [763]. Below Tv, the de resistivity increases almost exponentially with decreasing temperature.…”

Section: Transport Phenomena and The Fluctuation Of Chargementioning

confidence: 99%