The in-plane magnetic field penetration depth (λ ab ) in single-crystal La1.83Sr0.17CuO4 was investigated by means of the muon-spin rotation (µSR) technique. The temperature dependence of λ

In its orthorhombic T d polymorph, MoTe2 is a type-II Weyl semimetal, where the Weyl fermions emerge at the boundary between electron and hole pockets. Non-saturating magnetoresistance and superconductivity were also observed in T d-MoTe2. Understanding the superconductivity in T d-MoTe2, which was proposed to be topologically non-trivial, is of eminent interest. Here, we report high-pressure muon-spin rotation experiments probing the temperature-dependent magnetic penetration depth in T d-MoTe2. A substantial increase of the superfluid density and a linear scaling with the superconducting critical temperature T c is observed under pressure. Moreover, the superconducting order parameter in T d-MoTe2 is determined to have 2-gap s-wave symmetry. We also exclude time-reversal symmetry breaking in the superconducting state with zero-field μSR experiments. Considering the strong suppression of T c in MoTe2 by disorder, we suggest that topologically non-trivial s +− state is more likely to be realized in MoTe2 than the topologically trivial s ++ state.

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The in-plane magnetic penetration depth ab of the iron selenide superconductor with the nominal composition FeSe 0.85 was studied by means of muon-spin rotation. The measurements of ab −2 ͑T͒ are inconsistent with a simple isotropic s-wave type of the order parameter but are rather in favor of two-gap ͑s + s͒ and anisotropic s-wave order parameter symmetries, thus implying that the superconducting energy gap in FeSe 0.85 contains no nodes.

Recent EPR and susceptibility measurements in La 1Ϫx Ca x MnO 3 support the existence of a bottleneck EPR regime up to 1000 K quantitatively. The EPR linewidth and electrical conductivity follow the same temperature dependence in the range of 250 to 650 K predicted by the small polaron hopping model. This indicates that spin-lattice relaxation in manganates is due to the relaxation of spins of e g Jahn-Teller polarons to the lattice.