  The spin-1/2 XXZ Heisenberg magnet is considered for the case of the
anisotropy parameter tending to infinity (so-called, Ising limit). A thermal
correlation function of the ferromagnetic string is calculated over the ground
state. The approach to the calculation of the correlation functions in the
limit of infinite anisotropy is based on the observation that the wave function
is expressed in terms of the symmetric Schur functions. It is demonstrated that
at low temperatures the amplitude of the asymptotical expression of this
correlation function is proportional to the squared numbers of strict boxed
plane partitions.
