Asymmetric response of magnetic impurity in Bernal-stacked bilayer honeycomb lattice**Project supported by the National Natural Science Foundation of China (Grant No. 11604166), the Zhejiang Open Foundation of the Most Important Subjects, China (Grant No. xkzw11609), and the K. C. Wong Magna Fund in Ningbo University, China.

Abstract

We utilize the Hirsch–Fye quantum Monte Carlo method to investigate the local moment formation of a magnetic impurity in a Bernal-stacked bilayer honeycomb lattice. A tight-binding model with the two most significant inter-layer hoppings, t1 between pairs of dimer sites and t3 between pairs of non-dimer sites, is used to describe the kinetic energy of the system. The local moment formed shows an asymmetric response to the inter-layer hoppings depending on which sublattice the impurity is coupled to. In the dimer and non-dimer couplings, the effects of t1 and t3 onto the local moment are quite opposite. When tuning the local moment, this asymmetric response is observed in a wide parameter range. This asymmetric response is also discussed by the computations of spectral densities, as well as correlation functions between the magnetic impurity and the conduction electrons.