Investigation of dimensionality in superconducting NbN thin film samples with different thicknesses and NbTiN meander nanowire samples by measuring the upper critical field

Nazir Mudassar^{1, 2}, Yang Xiaoyan³, Tian Huanfang¹, Song Pengtao^{1, 2}, Wang Zhan^{1, 2}, Xiang Zhongcheng¹, Guo Xueyi¹, Jin Yirong¹, You Lixing³, Zheng Dongning^{1, 2, 4, †}

(a) Angular dependence of upper critical field graph for NbN 100 nm is taken at temperature 11.25 K. The upper critical field shows maxima for both parallel and perpendicular orientations. The H_c2 peak for the perpendicular orientation is believed to be due to the columnar structures formed during the growth of the thick films. (b) TEM image clearly shows columnar in NbN 100 nm film. The top, middle, and bottom layers represent the substrate, film, and protection layer, respectively. The red arrow indicates the one typical columnar structure.