  The distribution of Yang-Lee zeros in the ferromagnetic Ising model in both
two and three dimensions is studied on the complex field plane directly in the
thermodynamic limit via the tensor network methods. The partition function is
represented as a contraction of a tensor network and is efficiently evaluated
with an iterative tensor renormalization scheme. The free-energy density and
the magnetization are computed on the complex field plane. Via the
discontinuity of the magnetization, the density of the Yang-Lee zeros is
obtained to lie on the unit circle, consistent with the Lee-Yang circle
theorem. Distinct features are observed at different temperatures---below,
above and at the critical temperature. Application of the tensor-network
approach is also made to the $q$-state Potts models in both two and three
dimensions and a previous debate on whether, in the thermodynamic limit, the
Yang-Lee zeros lie on a unit circle for $q>2$ is resolved: they clearly do not
lie on a unit circle except at the zero temperature. For the Potts models
(q=3,4,5,6) investigated in two dimensions, as the temperature is lowered the
radius of the zeros at a fixed angle from the real axis shrinks exponentially
towards unity with the inverse temperature.
