  A spin-1/2 Ising-Heisenberg branched chain constituted by regularly
alternating Ising spins and Heisenberg dimers involving an additional side
branching is exactly solved in a magnetic field by the transfer-matrix method.
The spin-1/2 Ising-Heisenberg branched chain involves two different Ising and
one Heisenberg coupling constants. The overall ground-state phase diagram is
formed by three different ground states emergent depending on a mutual
interplay between the magnetic field and three considered coupling constants:
the modulated quantum antiferromagnetic phase, the quantum ferrimagnetic phase,
and the classical ferromagnetic phase. It is shown that the interaction
anisotropy connected to two different Ising coupling constants substantially
influences a breakdown of the intermediate one-half magnetization plateau,
which represents a macroscopic manifestation of the quantum ferrimagnetic
phase.
