Title: Single Magnetic Impurity in Tilted Dirac Surface States,
Abstract: We utilize variational method to investigate the Kondo screening of a
spin-1/2 magnetic impurity in tilted Dirac surface states with the Dirac cone
tilted along the $k_y$-axis. We mainly study about the effect of the tilting
term on the binding energy and the spin-spin correlation between magnetic
impurity and conduction electrons, and compare the results with the
counterparts in a two dimensional helical metal. The binding energy has a
critical value while the Dirac cone is slightly tilted. However, as the tilting
term increases, the density of states around the Fermi surface becomes
significant, such that the impurity and the host material always favor a bound
state. The diagonal and the off-diagonal terms of the spin-spin correlation
between the magnetic impurity and conduction electrons are also studied. Due to
the spin-orbit coupling and the tilting of the spectra, various components of
spin-spin correlation show very strong anisotropy in coordinate space, and are
of power-law decay with respect to the spatial displacements.