Sharma N, Vugts P, Daniels C, Keuning W, Kohlhepp J T, Kurnosikov O, Koopmans B
Department of Applied Physics, Center for NanoMaterials and COBRA Research Institute, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
Nanotechnology. 2014 Dec 12;25(49):495201. doi: 10.1088/0957-4484/25/49/495201. Epub 2014 Nov 20.
We report multi-channel electron transport in nano-contacts fabricated using focused electron beam induced deposited (FEBID) cobalt and focused ion beam induced deposited (FIBID) tungsten. Anomalous Andreev reflection (AR) effect is observed to which the conventional Blonder-Tinkham-Klapwijk (BTK) fit cannot be applied. In specific, we have observed multiple number of shoulders near the AR peak, whose origin is unknown in literature. We explain this effect based on a simple model that takes into account the material properties of the FIBID grown W superconductor, as well as the specific interface properties that are an outcome of using FEBID/FIBID as a fabrication technique. We show that numerical calculations using the BTK approximation based on the consideration of multiple channels generate similar shoulders as we observed in the AR experiments. Electrical measurements and x-ray photoemission spectroscopy carried out on FIBID W deposits puts additional evidence towards multi-channel current transport occuring at the interface of the nanocontacts.
我们报道了在使用聚焦电子束诱导沉积（FEBID）钴和聚焦离子束诱导沉积（FIBID）钨制造的纳米接触中的多通道电子输运。观察到反常安德列夫反射（AR）效应，传统的布隆德 - 廷克汉姆 - 克拉普维克（BTK）拟合方法无法适用。具体而言，我们在AR峰附近观察到多个肩峰，其起源在文献中尚不清楚。我们基于一个简单模型来解释这种效应，该模型考虑了FIBID生长的W超导体的材料特性，以及使用FEBID/FIBID作为制造技术所产生的特定界面特性。我们表明，基于多通道考虑使用BTK近似进行的数值计算产生了与我们在AR实验中观察到的类似的肩峰。对FIBID W沉积物进行的电学测量和X射线光电子能谱为纳米接触界面处发生的多通道电流输运提供了额外证据。
