近日，中国科学院物理研究所的金奎娟及其研究团队与南方科技大学的王善民等人合作并取得一项新进展。经过不懈努力，他们对全氮铁磁体/超导体界面上的强各向异性序参量进行研究。相关研究成果已于2024年2月26日在国际知名学术期刊《中国物理快报》上发表。

该研究团队成功制备了一种由超导氮化钛（SC-TiN）和铁磁氮化铁（FM-Fe₃N）组成的异质结构，其化学成分精确且原子界面清晰。该Fe₃N/TiN异质结构展现出显著的磁电阻磁各向异性，并且对外部扰动高度敏感。当TiN接近Fe₃N时，其超导转变温度（T_C）和临界场均受到显著抑制。研究人员在接近T_C（约1.25K）的温度下观察到了界面自旋取向的有趣竞争现象。这些发现不仅为研究超导体与铁磁体之间的相互作用提供了新的材料体系，还为超导自旋电子器件领域的研究和应用奠定了潜在基础。

据悉，超导体和铁磁体（SC/FM）之间的邻近效应对于探究其界面上发生的自旋竞争至关重要。这种竞争主要源自库珀对与铁磁交换相互作用之间的相互作用。然而，由于制造高质量SC/FM界面的难度极大，关于过渡金属氮化物（TMNs）之间的邻近效应的研究相对稀少。

附：英文原文

Title: Strong Anisotropic Order Parameters at All-Nitride Ferromagnet/Superconductor Interfaces

Author: Qiao Jin^1†, Meng Yang^1,2†, Guozhu Song³, Nan Zhao³, Shengru Chen^1,2, Haitao Hong^1,2, Ting Cui^1,2, Dongke Rong^1,2, Qianying Wang^1,2, Yiyan Fan¹, Chen Ge^1,2,4, Can Wang^1,2,4, Jiachang Bi⁵, Yanwei Cao⁵, Liusuo Wu³, Shanmin Wang³, Kui-Juan Jin^1,2,4*, Zhi-Gang Cheng^1,4*, and Er-Jia Guo^1,2*

Issue&Volume: 2024-02-26

Abstract: Proximity effects between superconductors and ferromagnets (SC/FM) hold paramount importance in comprehending the spin competition transpiring at their interfaces. This competition arises from the interplay between Cooper pairs and ferromagnetic exchange interactions. The proximity effects between transition metal nitrides (TMNs) are scarcely investigated due to the formidable challenges of fabricating high-quality SC/FM interfaces. We fabricated heterostructures comprising SC titanium nitride (TiN) and FM iron nitride (Fe₃N) with precise chemical compositions and atomically well-defined interfaces. The magnetoresistance of Fe₃N/TiN heterostructures shows a distinct magnetic anisotropy and strongly depends on the external perturbations. Moreover, the superconducting transition temperature T_C and critical field of TiN experience notable suppression when proximity to Fe₃N. We observe the intriguing competition of interfacial spin orientations near T_C (～1.25K). These findings not only add a new materials system for investigating the interplay between superconductor and ferromagnets, but also potentially provide a building block for future research endeavors and applications in the realms of superconducting spintronic devices.

DOI: 10.1088/0256-307X/41/2/027402

Source: https://cpl.iphy.ac.cn/10.1088/0256-307X/41/2/027402