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arXiv 1802.08787cond-mat.supr-con
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I型和II Weyl超导体的磁性

Magnetic properties of Type I and II Weyl Superconductors

Baruch Rosenstein, B. Ya. Shapiro, Dingping Li, I. Shapiro

摘要:

在一定的压力和化学组成范围内,I型和II型Weyl半金属(当Dirac锥倾斜参数为$κ>1$时)都观察到了超导性。基于微观声子介导对模型,研究了这些超导体的磁性。用Gorkov方法导出了Ginzburg-Landau有效序参量理论,并用于确定各向异性相干长度,穿透深度确定了层状材料的Abrikosov参数,并应用于最近在$% MoTe_{2}$上进行的广泛实验。对第二类超导体,比较了临界场$κ=1$和$H_{c1}$对倾斜参数$κ$(由压力决定)的依赖关系.估算了热涨落的强度,发现热涨落的强度足以引起$H_{c2}$附近的Abrikosov涡旋晶格熔化。熔化线的计算和实验提供的波动是三维的I型相(大压力)和二维的II型相(小压力)是一致的。

英文摘要:

Superconductivity was observed in certain range of pressure and chemical composition in Weyl semi-metals of both the type I and type II (when the Dirac cone tilt parameter $κ>1$). Magnetic properties of these superconductors are studied on the basis of microscopic phonon mediated pairing model. The Ginzburg - Landau effective theory for the order parameter is derived using Gorkov approach and used to determine anisotropic coherence length, the penetration depth determining the Abrikosov parameter for a layered material and applied to recent extensive experiments on $% MoTe_{2}$. It is found that superconductivity is of second kind near the topological transition at $κ=1$, but becomes first kind away from it. For the superconductors of the second kind the dependence of critical fields $H_{c2}$ and $H_{c1}$ on the tilt parameter $κ$ (governed by pressure) is compared with the experiments. Strength of thermal fluctuations is estimated and its is found that they are strong enough to cause Abrikosov vortex lattice melting near $H_{c2}$. The melting line is calculated and is consistent with experiments provided the fluctuations are three dimensional in the type I phase (large pressure) and two dimensional in the type II phase (small pressure).

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