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arXiv 0909.4323cond-mat.supr-con
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铁磁约瑟夫森结中的相控邻近效应:DOS和电子specific heat的计算

Phase-controlled proximity-effect in ferromagnetic Josephson junctions: calculation of DOS and electronic specific heat

Mohammad Alidoust, Jacob Linder, Gholamreza Rashedi, Asle Sudbø

摘要:

研究了低温下带s波超导引线的脏铁磁S $\mid$ F $\mid$ S约瑟夫森结的热力学性质。我们采用一组现实的参数和边界条件,考虑一个统一的和非统一的交换场的形式的布洛赫畴壁铁磁层的完整的数值解。自旋活性界面的影响,通过微观的方法被纳入。我们主要研究了\textit{proximity effect}对系统的电子比热和态密度的影响,并通过超导相位差对系统的电子比热和态密度进行了调节。我们的主要结果是,在低温下,通过改变两个超导引线之间的相位差从0到接近$π$,可以实现系统的\textit{strongly modify the electronic specific heat}。对于交换场的小值$h\simeqΔ$,将发生比热的增强,而对于大值的$h$,通过增加超导引线之间的相位差来抑制比热。这些结果都解释在铁磁区的邻近改变DOS方面,我们讨论了可能的实验检测预测效果的方法。

英文摘要:

We study the thermodynamic properties of a dirty ferromagnetic S$\mid$F$\mid$S Josephson junction with s-wave superconducting leads in the low-temperature regime. We employ a full numerical solution with a set of realistic parameters and boundary conditions, considering both a uniform and non-uniform exchange field in the form of a Bloch domain wall ferromagnetic layer. The influence of spin-active interfaces is incorporated via a microscopic approach. We mainly focus on how the electronic specific heat and density of states (DOS) of such a system is affected by the \textit{proximity effect}, which may be tuned via the superconducting phase difference. Our main result is that it is possible to \textit{strongly modify the electronic specific heat} of the system by changing the phase difference between the two superconducting leads from 0 up to nearly $π$ at low temperatures. An enhancement of the specific heat will occur for small values $h\simeqΔ$ of the exchange field, while for large values of $h$ the specific heat is suppressed by increasing the phase difference between the superconducting leads. These results are all explained in terms of the proximity-altered DOS in the ferromagnetic region, and we discuss possible methods for experimental detection of the predicted effect.

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