Critical properties of six-state clock model on randomly frustrated 2D lattices*

We study the antiferromagnetic six-state clock model
on bond-diluted triangular lattice, which is randomly frustrated.
The corresponding pure system of the model experiences two separated
phase transitions, i.e., the Kosterlitz-Thouless (KT) transition of
magnetic ordering and the chiral ordering transition which occurs
at slightly higher temperature. Due to discrete symmetry of spins
there exists an additional KT transition at lower temperature,
separating the true (magnetic) and the quasi-long range order (QLRO).
As randomness is important for phase transition, it is desirable to
probe the role played by dilution in affecting the existing KT
transitions as well as the chiral ordering transition.
With the presence of bond dilution in the triangular lattice the system
is transformed from the fully frustrated into a randomly frustrated case.
As the energy of the model is represented by the multiple of $J/2$,
where $J$ is the coupling constant, we use Wang-Landau algorithm of
Monte Carlo method. Various concentrations of depleted bonds were simulated.
We observed a systematic decrease of critical temperatures,
both for the KT transition and chiral transition,
as the concentration of dilution increases. We obtained the phase diagram of the system.