  The strongly correlated spin-electron system on a diamond chain containing
localized Ising spins on its nodal lattice sites and mobile electrons on its
interstitial sites is exactly solved in a magnetic field using the
transfer-matrix method. We have investigated in detail all available ground
states, the magnetization processes, the spin-spin correlation functions around
an elementary plaquette, fermionic quantum concurrence and spin frustration. It
is shown that the fermionic entanglement between mobile electrons hopping on
interstitial sites and the kinetically-induced spin frustration are closely
related yet independent phenomena. In the ground state, quantum entanglement
only appears within a frustrated unsaturated paramagnetic phase, while thermal
fluctuations can promote some degree of quantum entanglement above the
non-frustrated ground states with saturated paramagnetic or classical
ferrimagnetic spin arrangements.
