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arXiv 1208.4760cond-mat.supr-concond-mat.mtrl-sci
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RbxFe2-ySe2的超导性和磁性:热处理对介观相分离的影响

Superconductivity and magnetism in RbxFe2-ySe2: Impact of thermal treatment on mesoscopic phase separation

S. Weyeneth, M. Bendele, F. von Rohr, P. Dluzewski, R. Puzniak, A. Krzton-Maziopa, S. Bosma, Z. Guguchia, R. Khasanov, Z. Shermadini, A. Amato, E. Pomjakushina,… 展开作者

S. Weyeneth, M. Bendele, F. von Rohr, P. Dluzewski, R. Puzniak, A. Krzton-Maziopa, S. Bosma, Z. Guguchia, R. Khasanov, Z. Shermadini, A. Amato, E. Pomjakushina, K. Conder, A. Schilling, H. Keller

摘要:

本文对不同生长态和退火态的RbxFe_(2-y)Se_(2-x)单晶的超导和正常态性质进行了深入的研究。磁化实验证明,退火的RbxFe 2-ySe 2在413 K,远低于相分离的开始Tp=489 K,既不改变磁性,也不超导性能的晶体。此外,退火在563 K,远高于Tp,抑制超导转变温度Tc,并导致伴随着铁磁杂质相的产生,这是发展与退火时间的反铁磁磁化率的增加。然而,在T= 488 K =Tp下退火使Tc增加到33.3 K,使超导转变尖锐,增加了下临界场,并加强了所施加磁场的屏蔽效率。电阻率测量的生长和最佳退火样品揭示了沿两个晶体学方向的上临界场的增加,以及其各向异性。μ子自旋旋转和扫描透射电子显微镜实验表明,在Tp以下的两相共存:磁性多数相的Rb 2Fe 4Se 5和非磁性少数相的Rb 0.5Fe 2Se 2。这两种显微镜技术表明,退火的标本只是在Tp不影响的两个阶段的体积分数,虽然样品中的磁场分布的变化很大。这表明,样品的微观结构,介观相分离所造成的,是修改的退火只是在Tp,导致的超导性能的RbxFe 2-ySe 2的改善和Tc的增强。

英文摘要:

An extended study of the superconducting and normal-state properties of various as-grown and post-annealed RbxFe2-ySe2 single crystals is presented. Magnetization experiments evidence that annealing of RbxFe2-ySe2 at 413 K, well below the onset of phase separation Tp=489 K, neither changes the magnetic nor the superconducting properties of the crystals. In addition, annealing at 563 K, well above Tp, suppresses the superconducting transition temperature Tc and leads to an increase of the antiferromagnetic susceptibility accompanied by the creation of ferromagnetic impurity phases, which are developing with annealing time. However, annealing at T=488K=Tp increases Tc up to 33.3 K, sharpens the superconducting transition, increases the lower critical field, and strengthens the screening efficiency of the applied magnetic field. Resistivity measurements of the as-grown and optimally annealed samples reveal an increase of the upper critical field along both crystallographic directions as well as its anisotropy. Muon spin rotation and scanning transmission electron microscopy experiments suggest the coexistence of two phases below Tp: a magnetic majority phase of Rb2Fe4Se5 and a non-magnetic minority phase of Rb0.5Fe2Se2. Both microscopic techniques indicate that annealing the specimens just at Tp does not affect the volume fraction of the two phases, although the magnetic field distribution in the samples changes substantially. This suggests that the microstructure of the sample, caused by mesoscopic phase separation, is modified by annealing just at Tp, leading to an improvement of the superconducting properties of RbxFe2-ySe2 and an enhancement of Tc.

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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