Anomalous flux flow resistivity in the two-gap superconductor MgB 2
Anomalous flux flow resistivity in the two-gap superconductor MgB 2
复制标题
双间隙超导体MgB 2 中的反常磁通流电阻率
DOI：
10.1103/physrevb.68.060501
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发表时间：
2003
影响因子：
3.7
通讯作者：
S. Tajima
中科院分区：
文献类型：
--
作者：
A. Shibata;M. Matsumoto;K. Izawa;Y. Matsuda;S. Lee;S. Tajima
通过微波表面阻抗测量与高质量${\mathrm{MgB}}_{2}$中涡流的纯粘性运动相关的通量流电阻率${\ensuremath{\rho}}_{f}$。磁通流电阻率表现出不寻常的场依赖性，在低场下有很强的增强，这与传统的横波超导体明显不同。在 $\mathit{H}\ensuremath{\Vert}\mathrm{ab}$ 平面中清楚地观察到分隔两个具有不同 ${\ensuremath{\rho}}_{f}$ 斜率的不同通量流动状态的交叉场。不寻常的 H 依赖性表明，${\mathrm{MgB}}_{2}$ 中两个大小截然不同的超导间隙在涡动力学中表现出来，并且几乎同样对能量耗散有同样的贡献。还讨论了两个不同频带中的载流子散射率，并与热容和热导率结果进行了比较。
The flux flow resistivity ${\ensuremath{\rho}}_{f}$ associated with purely viscous motion of vortices in high-quality ${\mathrm{MgB}}_{2}$ was measured by microwave surface impedance. Flux flow resistivity exhibits unusual field dependence with strong enhancement at low field, which is markedly different to conventional s-wave superconductors. A crossover field which separates two distinct flux flow regimes having different ${\ensuremath{\rho}}_{f}$ slopes was clearly observed in $\mathit{H}\ensuremath{\Vert}\mathrm{ab}$ plane. The unusual H dependence indicates that two very differently sized superconducting gaps in ${\mathrm{MgB}}_{2}$ manifest in the vortex dynamics and almost equally contribute to energy dissipation. The carrier scattering rate in two different bands is also discussed with the present results, compared to heat-capacity and thermal-conductivity results.