Unconventional quantum oscillations in mesoscopic rings of spin-triplet superconductor Sr2RuO4
Unconventional quantum oscillations in mesoscopic rings of spin-triplet superconductor Sr2RuO4
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DOI：
10.1103/physrevb.87.081104
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发表时间：
2012-02
影响因子：
3.7
通讯作者：
X. Cai;Y. Ying;N. Staley;Y. Xin;D. Fobes;Tijiang Liu;Z. Mao;Ying Liu
中科院分区：
文献类型：
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作者：
X. Cai;Y. Ying;N. Staley;Y. Xin;D. Fobes;Tijiang Liu;Z. Mao;Ying Liu
人们发现奇宇称自旋三重态超导体 Sr2RuO4 具有奇异涡旋物理特征，包括困在双连接样本中的半通量量子以及在低场下形成涡旋晶格。本工作使用通过光刻和聚焦离子束在机械剥离的 Sr2RuO4 单晶上制造的环形装置，研究了这些涡旋态对 Sr2RuO4 介观样品的低温磁阻行为的影响。当磁场垂直于面内方向施加时，Sr2RuO4 的薄壁环被发现表现出明显的量子振荡，具有传统的全通量量子周期，尽管出乎意料的大振幅和振荡数量表明观察到的是涡流主导的磁阻振荡，而不是传统的小帕克斯效应。对于厚壁环，分别在高场和低场状态下发现了两个不同的量子振荡周期，我们认为这与这些厚壁环中涡旋晶格的“锁定”有关。迄今为止，在不存在面内场的情况下测量的任何样本中都没有发现半通量量子电阻振荡的证据。
Odd-parity, spin-triplet superconductor Sr2RuO4 has been found to feature exotic vortex physics including half-flux quanta trapped in a doubly connected sample and the formation of vortex lattices at low fields. The consequences of these vortex states on the low-temperature magnetoresistive behavior of mesoscopic samples of Sr2RuO4 were investigated in this work using ring device fabricated on mechanically exfoliated single crystals of Sr2RuO4 by photolithography and focused ion beam. With the magnetic field applied perpendicular to the in-plane direction, thin-wall rings of Sr2RuO4 were found to exhibit pronounced quantum oscillations with a conventional period of the full-flux quantum even though the unexpectedly large amplitude and the number of oscillations suggest the observation of vortex-flow-dominated magnetoresistance oscillations rather than a conventional Little-Parks effect. For rings with a thick wall, two distinct periods of quantum oscillations were found in high and low field regimes, respectively, which we argue to be associated with the "lock-in" of a vortex lattice in these thick-wall rings. No evidence for half-flux-quantum resistance oscillations were identified in any sample measured so far without the presence of an in-plane field.