Localized superconductivity in LaB$_6$ hexaboride with dynamic charge stripes

Type II superconductivity with $T_c\sim6\,$K is discovered in LaB$_6$. The critical fields are determined and the estimates for the coherence length $\xi(0)\sim240\,$Å, the Ginzburg–Landau parameter $\kappa_{\text{GL}}\sim2$, and the electron–phonon coupling constant $\lambda_{e{-}ph}\approx 0.75$ are obtained. Precision X-ray diffraction studies at $T = 30$ K reveal three-dimensional charge-stripe structures in LaB$_6$. The scenario of superconductivity localized near filamentary channels with a fluctuating electron density arising in the lanthanum hexaboride matrix is discussed.