排序方式: 共有78条查询结果,搜索用时 0 毫秒
61.
自旋极化扫描隧道显微术是一种新兴的表面自旋分辨技术,文章主要介绍了自旋极化的扫描隧道显微镜和扫描隧道谱实现表面自旋分辨的原理以及在各种磁性表面研究中的应用,采用自旋极化技术的扫描隧道显微镜可以测量表面磁结构,其空间分辨可以达到原子尺度,分辨率超过其他磁显微技术,而自旋极化扫描隧道谱不但可以分辨空间精细磁畴结构,而且能研究表面态的交换劈裂,文章作者还进一步提出了利用自旋极化扫描隧道显微镜实现自旋注入的设想。 相似文献
62.
63.
64.
Atomically fiat thin films of topological semimetal Na3Bi are grown on double-layer graphene formed on 6H SiC(0001) substrates by molecular beam epitaxy. By combined techniques of molecular beam epitaxy, scanning tunneling microscopy and angle resolved photoelectron spectroscopy, the growth conditions for NaaBi thin films on double-layer graphene are successfully established. The band structure of NaaBi grown on graphene is mapped along Г-M and Г-K; directions. Furthermore, the energy band of Na3Bi at higher energy is uncovered by doping Cs atoms on the surface. 相似文献
65.
超导作为一种宏观量子现象,其量子态波函数在理论上可以分为与氢原子模型类似的s波、p波、d波等。这些波函数的角动量量子数依次为0,1,2…,具有不同的对称性。在氢原子模型中,s波的波函数是各向同性的,而p波、d波的波函数在空间中存在很强的各向异性。其中,p波或d波的振幅在空间中的分布像两片或四片花瓣(此处考虑的是dx2-y2波),在从一片花瓣转向近邻花瓣时其相位部分变号。相比于氢原子模型,固体材料中除了存在完全各向同性的s波超导外,也可能存在一种角动量量子数为零但波函数振幅部分各向异性的配对。区分这种各向异性的s波与角动量量子数非零的波的关键是相位部分是否存在变号,相关的探测被称为对相位部分敏感的测量实验,简称相敏实验。为了开展相敏实验,我们可以从约瑟夫森效应出发。其经典的表达式为
I=Ic sin (φ1-φ2),
其中I是流过一个超导—绝缘层—超导三明治结构的电流,Ic是约瑟夫森临界电流(与超导波函数的振幅相关),φ1,2是组成约瑟夫森结的两个超导波函数的相位。这一式子说明,在没有电压的情况下存在一个非零的、由库珀对组成的电流穿过绝缘层。更重要的是,该电流与两个超导波函数的相位差直接相关。因此,测量约瑟夫森隧穿可以揭示波函数的相位信息,进而确定超导配对波函数的对称性。 相似文献
I=Ic sin (φ1-φ2),
其中I是流过一个超导—绝缘层—超导三明治结构的电流,Ic是约瑟夫森临界电流(与超导波函数的振幅相关),φ1,2是组成约瑟夫森结的两个超导波函数的相位。这一式子说明,在没有电压的情况下存在一个非零的、由库珀对组成的电流穿过绝缘层。更重要的是,该电流与两个超导波函数的相位差直接相关。因此,测量约瑟夫森隧穿可以揭示波函数的相位信息,进而确定超导配对波函数的对称性。 相似文献
66.
67.
Molecular beam epitaxy and superconductivity of stoichiometric FeSe and KxFe2_ySe2 crystalline films 下载免费PDF全文
Our recent progress in the fabrication of FeSe and KxFe2_ySe2 ultra thin films and the understanding of their superconductivity properties is reviewed. The growth of high-quality FeSe and KxFe2_ySe2 films is achieved in a well controlled manner by molecular beam epitaxy. The high-quality stoichiometric and superconducting crystalline thin films allow us to investigate the intrinsic superconductivity properties and the interplay between the superconductivity and the film thickness, the local structure, the substrate, and magnetism. In situ low-temperature scanning tunneling spectra reveal the nodes and the twofold symmetry in FeSe, high-temperature superconductivity at the FeSe/SrTiO3 interface, phase separation and magnetic order in KxFe2_ySe2, and the suppression of superconductivity by twin boundaries and Fe vacancies. Our findings not only provide fundamental information for understanding the mechanism of unconventional superconductivity, but also demonstrate a powerful way of engineering superconductors and raising the transition temperature. 相似文献
68.
Thermal stability of Mg2Si epitaxial film formed on Si(111) substrate by solid phase reaction 下载免费PDF全文
A single crystalline Mg2 Si film was formed by solid phase reaction(SPR) of a Si(111) substrate with an Mg overlayer capped with an oxide layer(s),which was enhanced by post annealing from room temperature to 100 ℃in a molecular beam epitaxy(MBE) system.The thermal stability of the Mg2 Si film was then systematically investigated by post annealing in an oxygen-radical ambient at 300℃,450℃ and 650 ℃,respectively.The Mg2 Si film stayed stable until the annealing temperature reached 450 ℃ then it transformed into amorphous MgO x attributed to the decomposition of Mg2 Si and the oxidization of dissociated Mg. 相似文献
69.
70.