Study of the superconducting properties of the new intermetallic compound ${{Zr}}_{1-x}{{Nb}}_{x}{B}_{2}$

Abstract

In this paper we report on the synthesis and the structural, electrical, magnetic and thermal analysis for the new material (0.01 x 0.05). A superconducting transition was observed for all x values studied, despite the non-superconducting matrix ZrB2, which indicates that the superconducting state is induced by the presence of Nb. The results show that the critical temperature increases with Nb content, reaching its maximum (Tc = 8.1 K) for x = 0.04. From the specific heat data we find a Sommerfeld constant of γ = 1.6 mJ molK−2 and a Debye temperature of = 615.5 K. Unconventional behaviors are observed in specific heat dependence with temperature and in diagram. These behaviors are investigated in versus T curve, where an upturn appears for K, and in versus dependence, which shows a clear deviation from BCS theory for low temperatures. Also, contrary to the conventional theories we found a positive curvature for temperatures near Tc in the lower critical field, besides an upturn around 2.3 K. We suggest that these behaviors possibly arise from multiband superconductivity in .

Phonon Dispersions as Indicators of Dynamic Symmetry Reduction in Superconductors

“…element doping or substitution) and do not display anomalies in their phonon dispersions. Such modification to the structure type, for example, adding boron to form NbB 2.5 [49], or substituting other elements, such as in Zr 1-x V x B 2 [50][51][52] or Zr 1-x Nb x B 2 [53] leads to superconductivity; as also suggested by Pickett et al [54] based on DFT calculations of AlB 2 -type structures. These minor modifications to the stoichiometry of an MB 2 structure are excellent examples of "fine-tuning" that achieves a dramatic change in material property.…”

Epitaxial Growth of Magnetron‐Sputtered ZrB2 Films on Si(100) Substrates

“…[3][4][5] While TMB 2 films were not implemented as diffusion barriers and interconnects in the semiconductor industry, they attract attention as refractory or protective coatings, conductive functional ceramics, [6] and as superconductors. [7][8][9] In particular, ZrB 2 can be made superconducting by doping, [10][11][12][13] stressing the need for being able to grow well-defined epitaxial ZrB 2 films. Today, the quality of diboride compound targets is greatly improved, and it has been possible to obtain films with high crystal quality on certain substrates, in particular using DC magnetron sputtering (DCMS) as seen, for example, in a study comparing the chemical bonding in a sputter target and in the ZrB 2 film on Al 2 O 3 sputtered from it.…”