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Lower Critical Field at Odds with A S-Wave Superconductivity in The New Superconductor $MgB_2$

S. L. Li·H. H. Wen·Z. W. Zhao·Y. M. Ni·Z. A. Ren·G. C. Che·H. P. Yang·Z. Y. Liu·Z. X. Zhao
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Abstract

The lower critical field $H_{c1}$ has been carefully measured on a well shaped cylindrical sample of the new superconductor $MgB_2$ fabricated by high pressure synthesis. The penetration depth $λ$ is calculated from the $H_{c1}$ data. It is found that a linear relation of $H_{c1}(T)$ appears in whole temperature region below $T_c$. Furthermore a finite slope of $dH_{c1}/dT$ and $dλ(T)/dT$ remains down to the lowest temperature (2 K). These are inconsistent with the expectation for a widely thought s-wave superconductivity in $MgB_2$.

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S. L. Li, H. H. Wen, Z. W. Zhao, Y. M. Ni, Z. A. Ren, G. C. Che, H. P. Yang, Z. Y. Liu, Z. X. Zhao. 2001-03-04. Lower Critical Field at Odds with A S-Wave Superconductivity in The New Superconductor $MgB_2$. https://doi.org/10.1103/physrevb.64.094522

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