Different melting behaviors in three thickness regimes:

˙Monolayer:

    crystal -- hexatic -- liquid

 

Ø˙Thin film (2-4 layers) :

    crystal -- liquid

    Melting starts from everywhere

 

Ø˙Thick film (>4 layer) :

    crystal -- crystal/liquid coexistence -- liquid

    Melting starts from grain boundaries in polycrystals and

    from crystal-wall interfaces in single crystals