H-T phase diagram and the nature of Vortex-glass phase in a quasi two-dimensional superconductor: Sn metal layer sandwiched between graphene sheets

The magnetic properties of a quasi two-dimensional superconductor, Sn-metal graphite (MG), are studied using DC and AC magnetic susceptibility. Sn-MG has a unique layered structure where Sn metal layer is sandwiched between adjacent graphene sheets. This compound undergoes a superconducting transition at Tc = 3.75 K at H = 0. The H-T diagram of Sn-MG is similar to that of a quasi two-dimensional superconductors. The phase boundaries of vortex liquid, vortex glass, and vortex lattice phase merge into a multicritical point located at T ∗ = 3.4 K and H = 40 Oe. There are two irreversibility lines denoted by Hgl (de Almeida-Thouless type) and Hgl′ (Gabay-Toulouse type), intersecting at T ′ 0= 2.5 K and H ′ 0 = 160 Oe. The nature of slow dynamic and nonlinearity of the vortex glass phase is studied.