Superconducting transition and phase diagram of single-crystal MgB2
Superconducting transition and phase diagram of single-crystal MgB2
复制标题
单晶MgB2的超导转变和相图
DOI：
10.1103/physrevb.67.012505
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发表时间：
2002
影响因子：
3.7
通讯作者：
S. Lee
中科院分区：
文献类型：
--
作者：
U. Welp;G. Karapetrov;W. Kwok;G. Crabtree;C. Marcenat;L. Paulius;T. Klein;J. Marcus;K. Kim;C. Jung;H. Lee;B. Kang;S. Lee
由磁化强度、磁输运和单晶比热测量确定了${\mathrm{MgB}}_{2}$的超导相图。零温面内相干长度为9.4 nm。在22 K时，超导各向异性系数从T_{c}$附近的2增加到4.5以上。对于$H\ensuremath{\parallel}c$，临界电流中的显著峰值效应发生在上临界场。表面超导状态的证据是$H\ensuremath{\parallel}c$，这可能会导致广泛报道的\ensuremath{\gamma}值。
The superconducting phase diagram of ${\mathrm{MgB}}_{2}$ was determined from magnetization, magnetotransport, and single-crystal specific-heat measurements. A zero-temperature in-plane coherence length of 9.4 nm is determined. The superconducting anisotropy \ensuremath{\gamma} increases from a value around 2 near ${T}_{c}$ to above 4.5 at 22 K. For $H\ensuremath{\parallel}c$ a pronounced peak effect in the critical current occurs at the upper critical field. Evidence for a surface superconducting state is presented for $H\ensuremath{\parallel}c$ that might account for the widespread in reported values of \ensuremath{\gamma}.