Nucleation of superconductivity in finite metallic multilayers: Effect of the symmetry

Effect of geometrical symmetry on the angular dependence of the critical magnetic field in superconductor/normal metal multilayers

“…11 A specially designed movable shutter allowed the simultaneous deposition of the two samples with a different number of bilayers, N bil . 17 We have fabricated Nb/Pd samples in the same deposition run with N bil = 9 and 10, respectively. The relation between the thickness of Pd ͑d N ͒ and Nb ͑d S ͒ layers was d N = d S /2=10 nm.…”

“…[31][32][33][34][35][36] On the other hand, the finiteness of the multilayers samples ͑i.e., the precise position of the superconducting nucleus͒ has been found to be a very important parameter in determining, for example, the resistive transition to the superconducting state 16 and the shape of the H-T phase diagram. 17 From this viewpoint the survey of the H c ͑⌰͒ characteristics in multilayers with the possibility of finetuning the position of superconducting nucleus is of great significance at least for two reasons: first, because of the mutual relation between the H c ͑⌰͒ shape and the nucleation position of the superconducting phase and, second, because in multilayers it is possible to precisely control, change, and know the position where the superconducting phase nucleates.…”

“…37 We prepared Nb/ Pd samples with different geometrical symmetries in order to vary the position of the nucleation of the superconducting phase. 17 The angular measurements were performed on the same set of samples analyzed in our previous work in which we reported only the results of the H c temperature dependence. 17 We performed angular measurements in the temperature range where, according to the H c ͑T , ⌰ =0͒ result, samples are in 2D mode.…”

“…17 The angular measurements were performed on the same set of samples analyzed in our previous work in which we reported only the results of the H c temperature dependence. 17 We performed angular measurements in the temperature range where, according to the H c ͑T , ⌰ =0͒ result, samples are in 2D mode. However, in agreement with previous experimental works, 4,25,28 the measured H c ͑⌰͒ data were not described by the 2D Tinkham expression ͓Eq.…”

“…[2][3][4][5][6][7][8][9][10][11][12] In particular, rather comprehensive understanding of the nature of the dimensional crossover-namely, the transition from three-dimensional ͑3D͒ to two-dimensional ͑2D͒ mode upon a variation of the temperature T-leads to deeper insight into the interaction between the superconducting layers and into the superconducting phase nucleation. [13][14][15] Recently, 16,17 we have shown that the dimensionality of finite S/N multilayers can be influenced by the "odd-even" effect related to the sample finiteness ͑in particular, the number of bilayers, odd or even͒ which determines the nucleation position of the superconducting phase. 18 The angular dependence of H c can be of highest importance to get additional useful information about the structure of multilayers, about the interaction between S layers as well as between the adjacent S and N layers, and about the origin of the superconducting phase nucleation in anisotropic superconductors.…”