Temperature dependence of spin-polarization in FIS graphene junction

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Journal of Magnetism and Magnetic Materials Pub Date : 2025-02-17 DOI:10.1016/j.jmmm.2025.172870

Hamidreza Emamipour

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Abstract

We study the effect of temperature on spin polarization in graphene-based ferromagnet insulator superconductor (FIS) junctions, theoretically. Within the framework of BTK (Blonder Tinkham Klapwijk) theory we find that when

E_{F}

is selected near to

E_{x}

(where

E_{F}

and

E_{x}

represent Fermi energy and exchange field in the ferromagnet region) and temperature approaches to

T_{c}

spin-polarization gets 100%. This case implies the spin-polarization is generated by just one spin species i.e. spin-up current, (

I_{u}

). We also obtain a phase diagram

E_{x} - T

which distinguishes SAR (specular Andreev reflection) from NAR (normal Andreev reflection). Therefore, the proposed junction may be applied not only to create huge spin-polarization which is significant in spintronic-industry but also to discriminate SAR and NAR from each other which is important in fundamental condensed matter physics.

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FIS石墨烯结中自旋极化的温度依赖性

从理论上研究了温度对石墨烯基铁磁绝缘体超导体（FIS）结自旋极化的影响。在BTK （Blonder Tinkham Klapwijk）理论框架下，我们发现当EF选择在Ex附近（其中EF和Ex表示铁磁体区域的费米能量和交换场），温度接近Tc时，自旋极化得到100%。这种情况意味着自旋极化仅由一种自旋物质即自旋向上电流（Iu）产生。我们还得到了相图Ex−T，它区分了SAR（镜面安德烈夫反射）和NAR（正常安德烈夫反射）。因此，所提出的结不仅可以用于产生巨大的自旋极化，这在自旋电子学工业中具有重要意义，而且可以用于区分SAR和NAR，这在基础凝聚态物理中具有重要意义。

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来源期刊

Journal of Magnetism and Magnetic Materials 物理-材料科学：综合

CiteScore

5.30

自引率

11.10%

发文量

1149

审稿时长

59 days

期刊介绍： The Journal of Magnetism and Magnetic Materials provides an important forum for the disclosure and discussion of original contributions covering the whole spectrum of topics, from basic magnetism to the technology and applications of magnetic materials. The journal encourages greater interaction between the basic and applied sub-disciplines of magnetism with comprehensive review articles, in addition to full-length contributions. In addition, other categories of contributions are welcome, including Critical Focused issues, Current Perspectives and Outreach to the General Public. Main Categories: Full-length articles: Technically original research documents that report results of value to the communities that comprise the journal audience. The link between chemical, structural and microstructural properties on the one hand and magnetic properties on the other hand are encouraged. In addition to general topics covering all areas of magnetism and magnetic materials, the full-length articles also include three sub-sections, focusing on Nanomagnetism, Spintronics and Applications. The sub-section on Nanomagnetism contains articles on magnetic nanoparticles, nanowires, thin films, 2D materials and other nanoscale magnetic materials and their applications. The sub-section on Spintronics contains articles on magnetoresistance, magnetoimpedance, magneto-optical phenomena, Micro-Electro-Mechanical Systems (MEMS), and other topics related to spin current control and magneto-transport phenomena. The sub-section on Applications display papers that focus on applications of magnetic materials. The applications need to show a connection to magnetism. Review articles: Review articles organize, clarify, and summarize existing major works in the areas covered by the Journal and provide comprehensive citations to the full spectrum of relevant literature.