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arXiv 0901.2024cond-mat.supr-con
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含锥形磁铁的约瑟夫森结的临界电流

Critical current of a Josephson junction containing a conical magnet

Gábor B. Halász, J. W. A. Robinson, M. G. Blamire, James F. Annett

摘要:

计算了超导体/铁磁体/超导体(S/FM/S)约瑟夫森结的临界电流,其中FM层具有由面内旋转反铁磁相和面外铁磁相组成的锥形磁结构.鉴于现实的电子性能和磁结构,可以形成时,圆锥形磁铁,如Ho生长与多晶结构的薄膜形式的方法,如直流溅射和蒸发,我们已经模拟了这种情况下,在肮脏的限制与一个大的磁相干长度($ξ_f$)。这意味着电子平均自由程比归一化螺旋长度$λ/2π$小得多,归一化螺旋长度又比$ξ_f$小得多(其中$λ$是沿着FM的生长方向的完整螺旋的长度)。在这个物理上合理的限制,我们采用了线性化Usadel方程:我们发现,三重态的相关性是短期的,并表现在临界电流作为一个快速振荡的规模$λ/2π$。临界电流中的这些快速振荡叠加在与单重态相关性有关的较慢振荡上。两种振荡都在$ξ_f$尺度上衰减。我们推导出一个解析解,并描述了一种计算方法,用于获得作为圆锥形磁层厚度的函数的临界电流。

英文摘要:

We calculate the critical current of a superconductor/ferromagnetic/superconductor (S/FM/S) Josephson junction in which the FM layer has a conical magnetic structure composed of an in-plane rotating antiferromagnetic phase and an out-of-plane ferromagnetic component. In view of the realistic electronic properties and magnetic structures that can be formed when conical magnets such as Ho are grown with a polycrystalline structure in thin-film form by methods such as direct current sputtering and evaporation, we have modeled this situation in the dirty limit with a large magnetic coherence length ($ξ_f$). This means that the electron mean free path is much smaller than the normalized spiral length $λ/2π$ which in turn is much smaller than $ξ_f$ (with $λ$ as the length a complete spiral makes along the growth direction of the FM). In this physically reasonable limit we have employed the linearized Usadel equations: we find that the triplet correlations are short ranged and manifested in the critical current as a rapid oscillation on the scale of $λ/2π$. These rapid oscillations in the critical current are superimposed on a slower oscillation which is related to the singlet correlations. Both oscillations decay on the scale of $ξ_f$. We derive an analytical solution and also describe a computational method for obtaining the critical current as a function of the conical magnetic layer thickness.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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