Quantum transport through an impurity-free Corbino disk in bilayer graphene is investigated analytically, by the mode-matching method for effective Dirac equation, in the presence of uniform magnetic fields. Similarly as in the monolayer case (see Refs. [1,2]), conductance at the Dirac point shows oscillations with the flux piercing the disk area $\Phi_D$ characterized by the period $\Phi_0=2\,(h/e)\ln(R_{ \rm o}/R_{ \rm i})$, where $R_{ \rm o}$ ($R_{ \rm i}$) is the outer (inner) disk radius. The oscillations magnitude depends either on the radii ratio or on the physical disk size, with the condition for maximal oscillations reading $R_{ \rm o}/R_{ \rm i}\simeq\left[\,R_{ \rm i}t_{ \perp}/(2\hbar{ }v_{ F})\,\right]^{ 4/p}$ (for $R_{ \rm o}/R_{ \rm i}\gg{ }1$), where $t_\perp$ is the interlayer hopping integral, $v_F$ is the Fermi velocity in graphene, and $p$ is an { \em even} integer. { \em Odd}-integer values of $p$ correspond to vanishing oscillations for the normal Corbino setup, or to oscillations frequency doubling for the Andreev-Corbino setup. At higher Landau levels (LLs) magnetoconductance behaves almost identically in the monolayer and bilayer cases. A brief comparison with the Corbino disk in 2DEG is also provided in order to illustrate the role of chiral tunneling in graphene.
Categories: cond-mat.mes-hall