van der Waals π Josephson Junctions
van der Waals π Josephson Junctions
复制标题
DOI：
10.1021/acs.nanolett.2c01640
复制
发表时间：
2022-06-23
期刊：
影响因子：
10.8
通讯作者：
Mak, Kin Fai
中科院分区：
文献类型：
--
作者：
Kang, Kaifei;Berger, Helmuth;Mak, Kin Fai
铁磁体中的邻近感生超导电性可以在超导体-铁磁体-超导体异质结构中产生具有有限质心动量的库珀对，并稳定具有π相位差的约瑟夫森结（JJ）。二维层状超导和磁性材料的出现为实现具有原子级尖锐界面的π JJ提供了一个新的平台。在这里，我们证明了厚度驱动的0-π转变的JJ由NbSe 2（伊辛超导体）和Cr2 Ge 2 Te 6（铁磁半导体）。通过系统地增加Cr_2Ge_2Te_6弱连接的厚度，我们观察到在临界厚度为-8nm处的超导电流消失，然后是折返的超导电流。在临界厚度附近，我们进一步观察到在零面内磁场附近临界电流消失的异常超导干涉图样。它们表示形成0-pi JJ（具有0和pi区域），诱导Cr2 Ge 2 Te 6中的纳米级域。
Proximity-induced superconductivity in a ferromagnet can induce Cooper pairs with a finite center-of-mass momentum and stabilize Josephson junctions (JJs) with pi phase difference in superconductor-ferromagnet-superconductor heterostructures. The emergence of two-dimensional layered superconducting and magnetic materials promises a new platform for realizing pi JJs with atomically sharp interfaces. Here we demonstrate a thickness-driven 0-pi transition in JJs made of NbSe2 (an Ising superconductor) and Cr2Ge2Te6 (a ferromagnetic semiconductor). By systematically increasing the Cr2Ge2Te6 weak link thickness, we observe a vanishing supercurrent at a critical thickness of -8 nm, followed by a re-entrant supercurrent. Near the critical thickness, we further observe unusual supercurrent interference patterns with vanishing critical current around zero in -plane magnetic field. They signify the formation of 0-pi JJs (with both 0 and pi regions), induced the nanoscale domains in Cr2Ge2Te6.