Superconducting properties ofVNxsputtered films including spin fluctuations and radiation damage of stoichiometric VN

Abstract

We have made well-ordered, stoichiometric films of VN using reactive sputtering and studied the effects of disordering due to deviations from stoichiometry and radiation damage. An unexpected local minimum of T, for the well-ordered, stoichiometric VN was found. The principal result was that the peak in T, for substoichiometric VNO 96 can be shown to be consistent with a competition between spin fluctuations and electron-phonon coupling, but we find the effect of the former is smaller than previously predicted. The superconducting properties measured in radiation-damaged VN have been extrapolated to pure, stoichiometric VN.

Application of thin nanocrystalline VN film as a high-performance diffusion barrier between Cu and SiO2

“…We chose VN instead of TaN x as a widely used barrier for Cu metallization because of the high resistivity ͑180-270 ⍀ cm͒ [7][8][9] and phase instability of Ta-N compounds. 10 Thin films of VN, which are low in resistivity ͑40-100 ⍀ cm͒, 11,12 were used as coating or superconducting materials. [12][13][14] Therefore, we attempted to apply VN to an extremely thin barrier in a nanocrystalline structure.…”

Structure and superconductivity of VN–SiO2 films obtained by thermal nitridation of sol–gel derived coatings

“…VN exhibits good selectivity and stability [1,2], that makes it an important industrial catalyst. Moreover, VN is a superconductor with the transition temperature of ∼ 9 K [3,4] and may be used in several superconducting microelectronics applications.…”

Magnetic and superconducting properties of spin-fluctuation-limited superconducting nanoscale VNx

“…The J c -H curves correspond to the DM-H curves at different temperatures, and the H C2 -T curve presents normal superconducting features, although the H c2 is lower than for the corresponding bulk. [14][15][16] It is interesting to notice that coexistence and competition effects of the superconducting Cooper pairs and of the Pauli and field-polarized electrons (Figs. 3(b) and 3(c)) are present in the system, which has motivated us to conjecture the electron pairing and breaking mechanism.…”

“…Although experimental studies have been made on a few superconductors, such as MoGe, 1,5 Pb, 2 Nb, 5 Al, 10,11 Sn, 12 and even high temperature superconducting (SC) nanowires 13 in recent years, there are still controversies on what the expected properties of a onedimensional (1D) superconductor are. For the VN x superconductors, one more interesting feature is their spin fluctuation limited superconductivity, which make the superconducting transition temperature T c < 10 K, much lower than the theoretically predicted $30 K. [14][15][16] Achieving fully stoichiometric VN x with the NaCl structure is a difficult proposition. This is because the superconducting transition temperature (T c ) has a linear relationship with the x value.…”

“…This is because the superconducting transition temperature (T c ) has a linear relationship with the x value. 15 Single-phase samples have only been successfully prepared with x up to 0.93 and T c up to 9.8 K. 14 The N vacancies have dominated the SC T c and other SC properties, and should significantly influence the magnetic properties as well. The x can be determined from x-ray diffraction (XRD) through the lattice parameter and T c measurement results due to the linear variation of T c with x.…”