Evidence of Andreev bound states as a hallmark of the FFLO phase in κ-(BEDT-TTF)2Cu(NCS)2
Evidence of Andreev bound states as a hallmark of the FFLO phase in κ-(BEDT-TTF)2Cu(NCS)2
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DOI：
10.1038/nphys3121
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发表时间：
2014-12-01
期刊：
影响因子：
19.6
通讯作者：
Mitrovic, V. F.
中科院分区：
文献类型：
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作者：
Mayaffre, H.;Kraemer, S.;Mitrovic, V. F.
超导性是一种量子现象，其最简单的形式是由具有相反自旋的费米子配对成具有零净动量的状态。超导性是否可以发生在两种物质的数量不等的费米子系统中，这是凝聚态物理学或量子色动力学中的一个重要的悬而未决的问题。在凝聚态物质中，形成库珀对的自旋向上和自旋向下的电子之间的不平衡是由磁场引起的。这样一个不平衡的系统可以导致奇异的超导性，其中对获得有限的动量（2，3）。这种动量导致了一个空间不均匀的状态，由周期性交替的“正常”和“超导”区域组成。在这里，我们建立了这种状态的标志是空间局域化和自旋极化准粒子形成所谓的Andreev束缚态（ABS）的外观。这些都是通过我们的核磁共振（NMR）测量检测到的。
Superconductivity is a quantum phenomenon arising, in its simplest form, from the pairing of fermions with opposite spin into a state with zero net momentum. Whether superconductivity can occur in fermionic systems with an unequal number of two species distinguished by spin or flavour presents an important open question in condensed-matter physics or quantum chromodynamics(1). In condensed matter the imbalance between spin-up and spin-down electrons that form the Cooper pairs is induced by the magnetic field. Such an imbalanced system can lead to exotic superconductivity in which pairs acquire finite momentum(2,3). This momentum leads to a spatially inhomogeneous state consisting of periodically alternating 'normal' and 'superconducting' regions. Here, we establish that the hallmark of this state is the appearance of spatially localized and spin-polarized quasiparticles forming the so-called Andreev bound states (ABS). These are detected through our nuclear magnetic resonance (NMR) measurements.