Two-dimensional nature of superconductivity in the intercalated layered systems LixHfNCl and LixZrNCl: Muon spin relaxation and magnetization measurements
Two-dimensional nature of superconductivity in the intercalated layered systems LixHfNCl and LixZrNCl: Muon spin relaxation and magnetization measurements
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DOI：
10.1103/physrevb.69.134522
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发表时间：
2004-04-01
影响因子：
3.7
通讯作者：
Kojima, KM
中科院分区：
文献类型：
--
作者：
Ito, T;Fudamoto, Y;Kojima, KM
我们报告μ子自旋弛豫（muSR）和磁化强度测量，连同合成和表征，锂插层层状超导体LixHfNCl和LixZrNCl与/无共插THF（四氢呋喃）或碳酸丙烯酯。三维超流密度n（s）/m*（超导载流子密度/有效质量）以及二维超流密度n（s2 D）/m（ab）* [超导载流子的二维（2D）面积密度/ab平面有效质量]已经从磁场穿透深度λ（ab）的muSR结果导出。在垂直于HfN/ZrN的2D蜂窝层施加外部磁场的情况下观察到。在T-c与n（s2 D）/m（ab）* 的曲线图中，大多数结果接近于在欠掺杂的高T-c铜酸盐（HTSC）和层状有机BEDT（双（亚乙基二硫代））超导体中发现的线性关系。在没有THF插层的LixZrNCl中，x=0.17和0.4的超流密度和T-c没有显示出太大的差异，这让人想起一些过掺杂HTSC系统的muSR结果。结合ZrN/HfN层间平均层间距对Tc的依赖性的缺乏，这些结果表明，二维超流密度n（s2 D）/m（ab）* 是氮-氯化合物插层体系中Tc的主要决定因素。我们还报告muSR和磁化结果的磁通涡旋的脱钉，和磁化结果的上临界场H-C2和穿透深度λ。一个合理的协议之间获得的muSR和磁化强度估计的λ。在此基础上，我们讨论了氮化物-氯化物体系超导电性的二维性质。
We report muon spin relaxation (muSR) and magnetization measurements, together with synthesis and characterization, of the Li-intercalated layered superconductors LixHfNCl and LixZrNCl with/without cointercalation of THF (tetrahydrofuran) or propylene carbonate. The three-dimensional superfluid density n(s)/m* (superconducting carrier density/effective mass) as well as the two-dimensional superfluid density n(s2D)/m(ab)* [two-dimensional (2D) area density of superconducting carriers/ab-plane effective mass] have been derived from the muSR results of the magnetic-field penetration depth lambda(ab) observed with external magnetic field applied perpendicular to the 2D honeycomb layer of HfN/ZrN. In a plot of T-c versus n(s2D)/m(ab)*, most of the results lie close to the linear relationship found for underdoped high-T-c cuprate (HTSC) and layered organic BEDT (bis(ethylenedithio)) superconductors. In LixZrNCl without THF intercalation, the superfluid density and T-c for x=0.17 and 0.4 do not show much difference, reminiscent of muSR results for some overdoped HTSC systems. Together with the absence of dependence of T-c on average interlayer distance among ZrN/HfN layers, these results suggest that the 2D superfluid density n(s2D)/m(ab)* is a dominant determining factor for T-c in the intercalated nitride-chloride systems. We also report muSR and magnetization results on depinning of flux vortices, and the magnetization results for the upper critical field H-c2 and the penetration depth lambda. A reasonable agreement was obtained between muSR and magnetization estimates of lambda. We discuss the two-dimensional nature of superconductivity in the nitride-chloride systems based on these results.