  The spin-1/2 Ising-Heisenberg model on a diamond-decorated square lattice
exhibits an intriguing temperature-driven phase transition in a magnetic field
between a classical ferrimagnetic phase and a quantum monomer-dimer phase. A
generalized decoration-iteration transformation accurately maps the considered
model to an effective spin-1/2 Ising model on a square lattice with
temperature-dependent effective interactions and field, whereby the effective
field vanishes at the phase boundary separating the classical ferrimagnetic
phase from the quantum monomer-dimer phase. Typical features of the
magnetization, magnetic susceptibility and specific heat in the vicinity of
discontinuous and continuous thermal phase transitions between the classical
ferrimagnetic phase and the quantum monomer-dimer phase are elucidated.
