Akiho Takafumi, Irie Hiroshi, Nakazawa Yusuke, Sasaki Satoshi, Kumada Norio, Muraki Koji
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi 243-0198, Japan.
Nano Lett. 2024 Nov 20;24(46):14790-14796. doi: 10.1021/acs.nanolett.4c04223. Epub 2024 Nov 6.
We have fabricated a superconductor/semiconductor junction composed of Al and InAs using cleaved edge overgrowth. By exploiting the unique geometry with a thin Al/Pt/Al trilayer formed on the side surface of an in situ cleaved InAs quantum well heterostructure wafer, we achieve a superconducting critical field of ∼5 T, allowing superconductivity and quantum Hall (QH) effects to coexist down to filling factor ν = 3. Andreev reflection at zero magnetic field shows a conductance enhancement limited solely by the Fermi velocity mismatch, demonstrating a virtually barrier-free junction. Bias spectroscopy in the QH regime reveals the opening of a superconducting gap, with the reduced downstream resistance indicating electron-hole Andreev conversion. Our results, obtained in a new experimental regime characterized by a clean edge-contacted junction with a superconducting electrode narrower than the coherence length, open new avenues for both theoretical and experimental studies of the interplay between superconductivity and QH effects.
我们利用解理边缘过生长技术制备了由铝（Al）和砷化铟（InAs）组成的超导体/半导体结。通过在原位解理的InAs量子阱异质结构晶片侧面形成薄的Al/Pt/Al三层结构，利用其独特的几何结构，我们实现了约5 T的超导临界场，使得超导性和量子霍尔（QH）效应能够共存至填充因子ν = 3。零磁场下的安德列夫反射显示出仅受费米速度失配限制的电导增强，表明该结几乎无势垒。量子霍尔 regime中的偏置光谱揭示了超导能隙的打开，下游电阻的降低表明电子 - 空穴安德列夫转换。我们的结果是在一个新的实验 regime中获得的，其特征是具有比相干长度窄的超导电极的清洁边缘接触结，为超导性和量子霍尔效应之间相互作用的理论和实验研究开辟了新途径。
