Theory of inplane magnetoresistance in two-dimensional massless Dirac fermion system

We present the theory of the inplane magnetoresistance in two-dimensional massless Dirac fermion systems including the Zeeman splitting and the electron-electron interaction effect on the Landau level broadening within a random phase approximation. With the decrease in temperature, we find a characteristic temperature dependence of the inplane magnetoresistance showing a minimum followed by an enhancement with a plateau. The theory is in good agreement with the experiment of the layered organic conductor \alpha-(BEDT-TTF)_2I_3 under pressure. In-plane magnetoresistsnce of graphene is also discussed based on this theory.Comment: 5 pages, 3 figures; added discussions and typos correcte

Enhancement of antiferromagnetic correlations below superconducting transition temperature in bilayer superconductors

Motivated by the recent experiment in multilayered cuprate superconductors reporting the enhancement of antiferromagnetic order below the superconducting transition temperature, we study the proximity effect of the antiferromagnetic correlation in a bilayer system and also examine the possibility of a coexistence of antiferromagnetic order and superconductivity. We present the result of mean field theory that is consistent with the experiment and supports the proximity effect picture.Comment: 7 pages, 6 figures, added Fig.6, some comments, and reference