Magnetic field driven metal-insulator phase transition in planar systems

A theory of the magnetic field driven (semi)metal-insulator phase transition is developed for planar systems with a low density of carriers and a linear (i.e., relativisticlike) dispersion relation for low-energy quasiparticles. The general structure of the phase diagram of the theory with respect to the coupling constant, the chemical potential, and the temperature is derived in two cases, with and without an external magnetic field. The conductivity and resistivity as functions of temperature and magnetic field are studied in detail. An exact relation for the value of the ``offset'' magnetic field ${B}_{c},$ determining the threshold for the realization of the phase transition at zero temperature, is established. The theory is applied to the description of a recently observed phase transition induced by a magnetic field in highly oriented pyrolytic graphite.