近日，中国科学技术大学的陈仙辉&项子霁及其研究团队取得一项新进展。经过不懈努力，他们发现氧化物异质结构中由铁磁邻近引起的超导条纹。相关研究成果已于2024年3月11日在国际知名学术期刊《自然—物理学》上发表。
该研究团队在KTaO3和铁磁性EuO的界面处，发现了一种空间变化的超导态。通过电输运测量，他们观察到当电流分别沿着两个正交的平面方向施加时，超导性被破坏的临界温度和磁场存在显著差异。这种各向异性特性在低载流子密度样品中尤为显著，这些样品的特点是Ta 5d和Eu 4f电子之间存在强烈的耦合作用。
然而，在高载流子密度样品中，这种耦合作用减弱，超导性质呈现出各向同性。这一发现表明，超导条纹可能出现在界面上，其中相位相干性在界面的其余部分之前建立。这种现象是由与带填充相关的铁磁邻近效应所引起的。
据悉，磁性与超导配对之间的紧密联系在决定非常规超导态的出现中扮演着至关重要的角色。特别是，磁性能够在实际空间中调控铜基和铁基材料的超导配对。深入研究这一效应将有助于揭示非常规超导的机理。
附：英文原文
Title: Superconducting stripes induced by ferromagnetic proximity in an oxide heterostructure
Author: Hua, Xiangyu, Zeng, Zimeng, Meng, Fanbao, Yao, Hongxu, Huang, Zongyao, Long, Xuanyu, Li, Zhaohang, Wang, Youfang, Wang, Zhenyu, Wu, Tao, Weng, Zhengyu, Wang, Yihua, Liu, Zheng, Xiang, Ziji, Chen, Xianhui
Issue&Volume: 2024-03-11
Abstract: The intimate connection between magnetism and superconducting pairing plays a central role in determining the occurrence of unconventional superconducting states. In particular, magnetism can cause a modulation of superconducting pairing in real space in both copper-based and iron-based materials. Exploring this effect can shed light on the mechanism of unconventional superconductivity. Here we report on the discovery of a spatially varying superconducting state residing at the interface between KTaO3 and ferromagnetic EuO. Electrical transport measurements reveal different values of the critical temperature and magnetic field at which the superconductivity breaks down when current is applied along the two orthogonal in-plane directions. This anisotropy occurs in low-carrier-density samples that are characterized by strong coupling between the Ta 5d and Eu 4f electrons, whereas in high-carrier-density samples, the coupling is weakened and the superconducting properties become isotropic. Our observations imply the emergence of superconducting stripes where phase coherence is established ahead of the rest of the interface, arising from a band-filling-dependent ferromagnetic proximity.
DOI: 10.1038/s41567-024-02443-x
Source: https://www.nature.com/articles/s41567-024-02443-x