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arXiv 0912.2941cond-mat.supr-con
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铜氧化物超导体的无序和场致反铁磁性

Disorder- and Field-Induced Antiferromagnetism in Cuprate Superconductors

Markus Schmid, Brian M. Andersen, Arno P. Kampf, P. J. Hirschfeld

摘要:

低掺杂的高Tc材料的特点是库珀配对和反铁磁(AF)秩序之间的竞争。这些材料的超导(SC)状态与传统超导体之间的重要区别包括d波配对对称性和对磁扰动的显着磁响应,从而可以在杂质和涡旋核心周围形成自旋密度波(SDW)序的液滴。在一个简单的图片中,只要SC被局部抑制,SDW秩序就成核。在平均场论的d-波SC在一个外加磁场中,包括无序和哈伯德关联,我们表明,事实上,创建SDW秩序不是简单地由于抑制的SC序参量,而是由于相关诱导分裂的电子束缚态的扰动。由于束缚态的存在是由于准粒子轨道上的序参量的符号变化,因此诱导的SDW序是d波对称性的直接结果。此外,反相畴壁的形成对于获得正确的中子衍射测量的感生磁性的温度依赖性是重要的。

英文摘要:

The underdoped high-Tc materials are characterized by a competition between Cooper pairing and antiferromagnetic (AF) order. Important differences between the superconducting (SC) state of these materials and conventional superconductors include the d-wave pairing symmetry and a remarkable magnetic response to nonmagnetic perturbations, whereby droplets of spin-density wave (SDW) order can form around impurities and the cores of vortices. In a simple picture, whenever SC is suppressed locally, SDW order is nucleated. Within a mean-field theory of d-wave SC in an applied magnetic field including disorder and Hubbard correlations, we show in fact that the creation of SDW order is not simply due to suppression of the SC order parameter, but rather due to a correlation-induced splitting of the electronic bound state created by the perturbation. Since the bound state exists because of the sign change of the order parameter along quasiparticle trajectories, the induced SDW order is a direct consequence of the d-wave symmetry. Furthermore the formation of anti-phase domain walls is important for obtaining the correct temperature dependence of the induced magnetism as measured by neutron diffraction.

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