Localized Superconductivity in LaB6 Hexaboride with Dynamic Charge Stripes

Abstract

Type II superconductivity with T_c ∼ 6 K is discovered in LaB₆. The critical fields are determined and the estimates for the coherence length ξ(0) ∼ 240 Å, the Ginzburg−Landau parameter κ_GL ∼ 2, and the electron–phonon coupling constant λ_e−ph ≈ 0.75 are obtained. Precision X-ray diffraction studies at T = 30 K reveal three-dimensional charge-stripe structures in LaB₆. The scenario of superconductivity localized near filamentary channels with a fluctuating electron density arising in the lanthanum hexaboride matrix is discussed.