Variational Monte Carlo study on a magnetization process of the Kitaev honeycomb model under a magnetic field

Recently, the Kitaev model under a magnetic field has been intensively studied, because the magnetization processes offer useful information for characterizing the nature of the quantum spin liquid. It was reported that an intermediate state appears in the antiferromagnetic coupling Kitaev model (AF KM) under a magnetic field by several numerical methods such as Majorana mean field, exact diagonalization, and DMRG. However, these methods are not appropriate for highly accurate analyses of physical properties in the 2D system with large system sizes. To identify whether the intermediate state exists as the ground state of the AF KM under a magnetic field in the bulk limit, it should be necessary to use an accurate numerical method which is applicable to the large 2D system.
In this talk, we will report the magnetization process of the AF KM obtained by using the variational Monte Carlo (VMC) method. The trial wave function we used is the BCS wave function with the Jastrow correlation factor, which can exactly represent the ground state of the pure Kitaev model fermionized by the Jordan-Wigner transformation. We will also explain the details of VMC and its accuracy.