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arXiv 1609.01432cond-mat.supr-con
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铜酸盐结赝能隙区两对不同的涨落寿命和超电流的观测

Observation of two distinct pairs fluctuation lifetimes and supercurrents in the pseudogap regime of cuprate junctions

Gad Koren, Patrick A. Lee

摘要:

在赝能隙区的铜氧化物外延c-轴结上测量了对涨落超电流和反向寿命,其中$PrBa_2Cu_3O_{7-δ}$势垒夹在两个$YBa_2Cu_3O_{7-δ}$或掺杂的$YBa_2Cu_3O_y$电极之间,有或没有平行于a-b平面的磁场。所有的结都有一个$\rm T_c(high)\approx 85-90$ K和一个$\rm T_c(low)\approx 50-55$ K电极,使我们能够研究这两个温度之间的超电流对波动和逆寿命。在结与pseudogap电极在零场下,过量的电流,由于对波动观察到持续在温度高于$\rm T_c(low)$,在pseudogap制度,并高达约$\rm T_c(high)$。在电极中没有伪间隙的结中没有观察到这样的过量电流。在高于$\rm T_c(low)$的温度下测量的电导谱使用Scalapino [Phys. Rev. Lett. \textbf{24},1052(1970)]中描述的方法。我们发现,在赝能隙状态下,电导与电压的关系由位于非常宽的峰顶部的窄峰组成。这在赝隙电极中产生两个不同的对波动寿命,其相差高达约$\rm T_c(high)$的数量级。在面内场下,这两个寿命值保持分离在两个不同的组中,其随场的增加而适度变化。我们还发现,在我们的铜酸盐结中检测安培配对[Phys. Rev. X \textbf{4},031017(2014)]是不可行的,这是由于约瑟夫森涡旋穿透到超导电极中,其驱动了在退配对场之上的必要场。

英文摘要:

Pairs fluctuation supercurrents and inverse lifetimes were measured on epitaxial c-axis junctions of the cuprates in the pseudogap regime, with a $PrBa_2Cu_3O_{7-δ}$ barrier sandwiched in between two $YBa_2Cu_3O_{7-δ}$ or doped $YBa_2Cu_3O_y$ electrodes, with or without magnetic fields parallel to the a-b planes. All junctions had a $\rm T_c(high)\approx 85-90$ K and a $\rm T_c(low)\approx 50-55$ K electrodes, allowing us to study pairs fluctuation supercurrents and inverse life times in between these two temperatures. In junctions with a pseudogap electrode under zero field, an excesss current due to pair fluctuations was observed which persisted at temperatures above $\rm T_c(low)$, in the pseudogap regime, and up to about $\rm T_c(high)$. No such excess current was observed in junctions without a pseudo-gap in the electrode. The measured conductance spectra at temperatures above $\rm T_c(low)$ were fitted using a modified fluctuations model by Scalapino [Phys. Rev. Lett. \textbf{24}, 1052(1970)] of a junction with a serial resistance. We found that in the pseudo-gap regime, the conductance vs voltage consists of a narrow peak sitting on top of a very broad peak. This yielded two distinct pairs fluctuation lifetimes in the pseudogap electrode which differ by an order of magnitude up to about $\rm T_c(high)$. Under in-plane fields, these two lifetime values remain separated in two distinct groups, which varied with increasing field moderately. We also found that detection of Amperian pairing [Phys. Rev. X \textbf{4}, 031017 (2014)] in our cuprate junctions is not feasible, due to Josephson vortices penetration into the superconducting electrodes which drove the necessary field above the depairing field.

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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