We determine analytically the phase diagram of the toric code model in a parallel magnetic
field which displays three distinct regions. Our study relies on two high-order perturbative
expansions in the strong-and weak-field limits, as well as a large-spin analysis. Calculations
in the topological phase establish a quasiparticle picture for the anyonic excitations. We
obtain two second-order transition lines that merge with a first-order line, giving rise to a
multicritical point as recently suggested by numerical simulations. We compute the values of …

We determine analytically the phase diagram of the toric code model in a parallel magnetic
field which displays three distinct regions. Our study relies on two high-order perturbative
expansions in the strong-and weak-field limit, as well as a large-spin analysis. Calculations
in the topological phase establish a quasiparticle picture for the anyonic excitations. We
obtain two second-order transition lines that merge with a first-order line giving rise to a
multicritical point as recently suggested by numerical simulations. We compute the values of …