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arXiv 1508.04529cond-mat.supr-concond-mat.str-el
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K2Cr3As3和Rb2Cr3As3的穿透深度测量

Penetration depth measurements of K2Cr3As3 and Rb2Cr3As3

G. M. Pang, M. Smidman, W. B. Jiang, Y. G. Shi, J. K. Bao, Z. T. Tang, Z. F. Weng, Y. F. Wang, L. Jiao, J. L. Zhang, J. L. Luo, G. H. Cao, H. Q. Yuan

摘要:

新发现的具有准一维晶体结构的超导体A_2Cr_3As_3(A = K,Rb,Cs)引起了人们极大的兴趣。晶体结构由[Cr 3As 3]^(2-)的双壁管组成,沿c轴延伸。以前,我们报告的测量在伦敦的穿透深度的多晶样品的K2 Cr 3As 3使用隧道二极管振荡器为基础的技术,这表明在低温下的线性温度依赖性的变化,在超导能隙线节点的证据。在这里,我们报告类似的测量穿透深度的多晶Rb 2Cr 3As 3和几个单晶K2 Cr 3As 3,由两个不同的研究小组。单晶测量显示出与多晶样品相似的行为,低至0.9-1.2 K,其中观察到所有单晶样品的频移下降。这些结果进一步证实了K_2Cr_3As_3的节结超导性,表明超导配对态是非常规的。在暴露于空气后劣化的样品中观察到的不同低温行为强调,在测量之前必须适当地处理样品,因为A2 Cr 3As 3化合物对空气极其敏感,并且仅在显示急剧超导转变的样品中观察到穿透深度测量的节点超导性的证据。因此,需要进一步的工作来提高单晶的质量,并确定衰退的根源。

英文摘要:

The newly discovered superconductors A2Cr3As3 (A = K, Rb, Cs), with a quasi-one-dimensional crystal structure have attracted considerable interest. The crystal structure consists of double-walled tubes of [Cr3As3]^(2-) that extend along the c-axis. Previously we reported measurements of the change in London penetration depth of polycrystalline samples of K2Cr3As3 using a tunnel diode oscillator based technique, which show a linear temperature dependence at low temperatures, giving evidence for line nodes in the superconducting gap. Here we report similar measurements of the penetration depth for polycrystalline Rb2Cr3As3 and several single crystals of K2Cr3As3, prepared by two different research groups. The single crystal measurements show similar behavior to polycrystalline samples down to 0.9-1.2 K, where a downturn is observed in the frequency shift for all single crystal samples. These results give further evidence for nodal superconductivity in K2Cr3As3, which indicates that the superconducting pairing state is unconventional. The different low temperature behavior observed in samples which have deteriorated after being exposed to air, emphasises that it is necessary to properly handle the samples prior to being measured because the A2Cr3As3 compounds are extremely air sensitive and evidence for nodal superconductivity from penetration depth measurements is only observed in the samples which display a sharp superconducting transition. Therefore further work is required to improve the quality of single crystals and to identify the origin of the downturn.

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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