Open and closed Fermi surface contributions to the anomalous angular magnetoresistance of α-(BEDT-TTF) 2RbHg(SCN) 4

Anomalous angular magnetoresistance (AMR) in the quasi-two dimensional organic conductor α-(BEDT-TTF) ₂RbHg(SCN) ₄ is reported. The AMR appears as oscillations with sharp minima below the anitiferromagnetic ordering temperature. The period of these oscillations is anisotropic with respect to the plane of rotation cutting through the conducting layers. Above the ordering temperature, the nature of the AMR changes fundamentally. We propose a model for the AMR that incorporates both open and closed Fermi surfaces, and discuss how temperature and field dependent behaviors of the individual FS contribute to the conductivity.