On electron transport in ZrB12, ZrB2, and MgB2 in normal state

Gasparov, V. A.; Kulakov, M. P.; Sidorov, N. S.; Зверькова, И. И.; Filipov, V. B.; Lyashenko, A. B.; Paderno, Yu. B.

doi:10.1134/1.1825116

Cited by 16 publications

(29 citation statements)

References 20 publications

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“…Despite the fact that ZrB 12 contains mostly boron, its room temperature resistivity is only four times larger than that of MgB 2 and ZrB 2 [2], while the residual resistivity is ten times larger. The resistivity ratio of ZrB 12 (R(300 K)/R(6 K) ≃ 4) is rather low compared to single crystal value 10 [23].…”

Section: Methodsmentioning

confidence: 99%

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Electron transport, penetration depth, and the upper critical magnetic field in ZrB12 and MgB2

Gasparov

Sidorov

Зверькова

et al. 2005

J. Exp. Theor. Phys.

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We report on the synthesis and measurements of the temperature dependence of resistivity, ρ(T ), the penetration depth, λ(T ), and upper critical magnetic field, Hc2(T ), for polycrystalline samples of dodecaboride ZrB12 and diboride MgB2. We conclude that ZrB12 as well as MgB2 behave like simple metals in the normal state with usual Bloch-Grüneisen temperature dependence of resistivity and with rather low resistive Debye temperature, TR = 280 K, for ZrB12 (as compared to MgB2 with TR = 900 K). The ρ(T ) and λ(T ) dependencies of these samples reveal a superconducting transition of ZrB12 at Tc = 6.0 K. Although a clear exponential λ(T ) dependence in MgB2 thin films and ceramic pellets was observed at low temperatures, this dependence was almost linear for ZrB12 below Tc/2. These features indicate s-wave pairing state in MgB2, whereas a d-wave pairing state is possible in ZrB12. A fit to the data gives a reduced energy gap 2∆(0)/kBTc = 1.6 for MgB2 films and pellets, in good agreement with published data for 3D π -sheets of the Fermi surface. Contrary to conventional theories we found a linear temperature dependence of Hc2(T ) (Hc2(0) = 0.15 T ) for ZrB12.

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Section: Methodsmentioning

confidence: 99%

“…In contrast ZrB 12 data display nearly zero T 2 term. In general, there are many scattering processes responsible for the T 2 term in ρ(T ) of metals [23]. In particular, umklapp e-e scattering strongly contributes to this term.…”

Section: Electron Transportmentioning

confidence: 99%

Electron transport, penetration depth, and the upper critical magnetic field in ZrB12 and MgB2

Gasparov

Sidorov

Зверькова

et al. 2005

J. Exp. Theor. Phys.

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“…Different conclusions were obtained in the literature by assuming that the Debye temperature has a value between 270 and 300 K and remains constant at least up to 25 K. [13][14][15] The latter assumption is obviously not supported by specific-heat measurements ͑Fig. 4͒; the initial Debye temperature is close to 1000 K and the continuum approximation F͑͒ ϰ 2 does not hold beyond 10 K. At 25 K the deviation with respect to the initial C phonon ͑T͒ ϰ T 3 law is as high as 300%.…”

Section: Resistivity and Electron-phonon Couplingmentioning

confidence: 99%

“…11,12 Similar discrepancies appear in the characterization of phonons. The Debye temperature is reported to be D = 270-300 K according to transport, [13][14][15] but 930 K according to early specific-heat measurements. 3 Magnetic properties also are controversial: the upper critical field H c2 ͑0͒ is reported to be in the range of 1100 to over 2000 G according to PCS, radio-frequency susceptibility, and transport, 11,13 but only 390 G according to dc magnetization.…”

Section: Introductionmentioning

confidence: 99%

Specific heat, magnetic susceptibility, resistivity and thermal expansion of the superconductorZrB12

et al. 2005

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In an attempt to clarify conflicting published data, we report new measurements of specific heat, resistivity, magnetic susceptibility, and thermal expansivity up to room temperature for the 6 K superconductor ZrB 12 , using well-characterized single crystals with a residual resistivity ratio Ͼ9. The specific heat gives the bulk result 2⌬͑0͒ / k B T c = 3.7 for the superconducting gap ratio, and excludes multiple gaps and d-wave symmetry for the Cooper pairs. The Sommerfeld constant ␥ n = 0.34 mJ K −2 gat −1 and the magnetic susceptibility = −2.1 ϫ 10 −5 indicate a low density of states at the Fermi level. The Debye temperature D is in the range 1000-1200 K near zero and room temperature, but decreases by a factor of ϳ2 at ϳ35 K. The specific heat and resistivity curves are inverted to yield approximations of the phonon density of states F͑͒ and the spectral electron-phonon scattering function ␣ tr 2 F͑͒, respectively. Both unveil a 15 meV mode, attributed to Zr vibrations in oversized B cages, which gives rise to electron-phonon coupling. The thermal expansivity further shows that this mode is anharmonic, while the vanishingly small discontinuity at T c establishes that the cell volume is nearly optimal with respect to T c .

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“…СТРУКТУРА И СВОЙСТВА КИСЛОРОДОСОДЕРЖАЩИХ ПЛЁНОК MgB 2 343 мерно, при средних температурах (15-20 К) толщина плёнок совпа-дает с величиной глубины проникновения магнитного поля [24], в результате на графике рис. 9, a при этой температуре наблюдается резкая смена одного типа зависимости на другой.…”

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Crystal Structure and Properties of the Oxide-Containing Magnesium Diboride Films

Prikhna¹,

Shapovalov²,

Shaternik³

et al. 2016

Metallofiz. Noveishie Tekhnol.

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On electron transport in ZrB12, ZrB2, and MgB2 in normal state

Cited by 16 publications

References 20 publications

Electron transport, penetration depth, and the upper critical magnetic field in ZrB12 and MgB2

Electron transport, penetration depth, and the upper critical magnetic field in ZrB12 and MgB2

Specific heat, magnetic susceptibility, resistivity and thermal expansion of the superconductorZrB12

Crystal Structure and Properties of the Oxide-Containing Magnesium Diboride Films

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