Interlayer Tunneling In Stacked Junctions Of High Temperature Superconductors, Cdw Materials And Graphite

Abstract

Abstract.A short review on interlayer tunneling studies of the stacked junctions of layered high temperature superconductors (HTSC), charge density wave (CDW) materials and graphite is presented. We specify individual features of each class of these materials and common features of interlayer tunneling. They are characterized by the layered crystalline structure of those materials. We emphasize the importance of the phase interlayer coupling in superconducting or CDW electron condensed states that provides interlayer coherent transport. We found that breaking of the phase coherence often happens via formation of phase topological defects (phase vortices) in one elementary junction of the stack that gives an opportunity for interlayer tunneling spectroscopy.Keywords: interlayer tunneling, Bi 2 Sr 2 CaCu 2 O 8+x , N bSe 3 , T aS +3 , KM o 6 O 17 , graphite, energy gap, pseudogap, conductance peak IntroductionMany layered conducting materials of different classes as superconductors, CDW materials, semimetals (graphite) has a common microscopic arrangement where highly conducting elementary planes of atomic thickness are separated by isolating elementary layers of atomic thickness. Macroscopically, that is characterized by the enormously high anisotropy of the in-plane and the out-of-plane conductivity, achieving 10 3 -10 4 in those materials. Microscopically, the interlayer tunneling is associated with interlayer tunneling over intrinsic barriers. The method first appeared in studies of layered HTS materials [1] and later has been adapted to layered manganites [2], CDW materials [3] and graphite [4].

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