Layered Kondo Lattice Model for Quantum Critical β-YbAlB4

We analyze the magnetic and electronic properties of the quantum critical heavy fermion superconductor beta-YbAlB4, calculating the Fermi surface and the angular dependence of the extremal orbits relevant to the de Haas-van Alphen measurements. Using a combination of the realistic materials modeling and single-ion crystal field analysis, we are led to propose a layered Kondo lattice model for this system, in which two-dimensional boron layers are Kondo coupled via interlayer Yb moments in a J(z)=+/- 5/2 state. This model fits the measured single-ion magnetic susceptibility and predicts a substantial change in the electronic anisotropy as the system is pressure tuned through the quantum critical point.