Checkerboard patterns of charge stripes in the two-gap superconductor ZrB12

Inhomogeneous superconductivity was studied in ZrB12 (Tc 6 K) using heat capacity and x-ray diffraction data. Evidence of two-band superconductivity with two branches of upper critical field Hc2(Tc) is obtained in a magnetic field applied along the [110] axis of the crystal. On the contrary, at H || [100], a single dependence Hc2(Tc) was observed. This finding is consistent with the checkerboard-type patterns observed on the difference Fourier maps of the electron density distribution. These patterns are compared to those for the weakly coupled superconductor LuB12, Tc of which is 15 times lower than that of ZrB12. The probable nature of the two-gap superconductivity in ZrB12 is discussed.

Automated summary

Inhomogeneous superconductivity in ZrB12 was studied using heat capacity and x-ray diffraction data. Evidence of two-gap superconductivity was found when a magnetic field was applied along the [110] axis, while a single gap was observed when the magnetic field was applied along the [100] axis. These findings are consistent with the checkerboard-type patterns observed in the electron density distribution.