Electron transport, penetration depth and upper critical magnetic field of ZrB12 and MgB2
arXiv:cond-mat/0411116 · doi:10.1134/1.2010666
Abstract
We report on the synthesis and measurements of the temperature dependence of resistivity, R(T), the penetration depth, l(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-Gruneisen 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 R(T) and l(T) dependencies of ZrB12 reveal a superconducting transition at Tc=6.0 K. Although a clear exponential l(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 2D(0)/kTc=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) for ZrB12 (Hc2(0)=0.15 T).
arXiv comment8 pages, 10 figures, submitted to JETP
References in corpus (17)
- Superconductivity of metallic boron in MgB_2
- Two-gap superconductivity in MgB: clean or dirty?
- Phenomenological two-gap model for the specific heat of MgB_2
- Multiband model for tunneling in MgB2 junctions
- Direct evidence for two-band superconductivity in MgB_2 single crystals from directional point-contact spectroscopy in magnetic fields
- Anisotropy of the Upper Critical Field and Critical Current in Single Crystal MgB
- Multiband model for penetration depth in MgB2
- Thermal conductivity of single crystalline MgB_2
- Exponential Temperature Dependence of Penetration Depth in Single Crystal MgB_2
- Superconducting MgB(2) films via precursor post-processing approach
- Temperature dependence and anisotropy of the bulk upper critical field H_c2 of MgB_2
- High-pressure synthesis of superconducting Nb{1-x}B2 (x = 0-0.48) with the maximum Tc = 9.2 K
- Electronic structure and weak electron-phonon coupling in TaB
- Evidence for Surface Andreev Bound states in Cuprate Superconductors from Penetration Depth Measurements
- Structure and Superconducting Properties of "BeB_2"
- On the T-dependence of the magnetic penetration depth in unconventional superconductors at low temperatures: can it be linear?
- Characteristic features of the temperature dependence of the surface impedance in polycrystalline MgB samples