Ni-impurity effects on the superconducting gap of La_2-xSr_xCuO_4 studied from the magnetic field and temperature dependence of the electronic specific heat
Ni-impurity effects on the superconducting gap of La_2-xSr_xCuO_4 studied from the magnetic field and temperature dependence of the electronic specific heat
复制标题
从电子比热的磁场和温度依赖性研究Ni杂质对La_2-xSr_xCuO_4超导能隙的影响
DOI：
10.1103/physrevb.85.134522
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
M. Oda and M.Ido
中科院分区：
文献类型：
--
作者：
Toru Kurosawa;N. Momono;M. Oda and M.Ido
为了研究镍杂质对超导(SC)带隙的影响，系统地研究了(LSCNO)中电子比荷随磁场和温度的变化关系。在=0.15和=0.015的LSCNO中，在沿c轴施加磁场的情况下，()在=10K处的值增大。，，的增量遵循Volovik关系=，SC带线节点间隙的特征，具有类似于纯样品的预因子。随Ni浓度的增加，VS曲线上的-值增大，但在=0下，Sc反常呈波浪状，并与At呈线性依赖关系。有趣的是，随着的SC部分在LSCNO中的减少，与的减少成比例地减少。这些发现可以用一个简单的模型来解释，在这个模型中，Ni杂质在费米面的相干节点处的边缘，但在Sc带隙的节点处，导致了强的对破裂。LSCNO中Sc冷凝能的降低也可以用同样的模型来解释。
The magnetic field and temperature dependence of the electronic specific heathave been systematically investigated in(LSCNO) in order to study Ni-impurity effects on the superconducting (SC) gap. In LSCNO with= 0.15 and= 0.015, the value of() at= 0 K,, is enhanced under the magnetic fieldapplied along the c axis. The increment of,, follows the Volovik relation=, characteristic of the SC gap with line nodes, with prefactorsimilar to that of a pure sample. Theversuscurve under= 0 shows a-wave-like SC anomaly with an abrupt increase atand-linear dependence at, although the-value in theversuscurve increases with increasing Ni concentrations. Interestingly, as the SC part of,, decreases in LSCNO,is reduced in proportion to the decrease of. These findings can be explained phenomenologically by a simple model in which Ni impurities bring about strong pair breaking at the edges of the coherent nodal part of the Fermi surface but in the vicinity of the nodes of the SC gap. The reduction of the SC condensation energyin LSCNO, evaluated fromat, is also understood by the same model.