  We report physical and structural properties of single-crystal Ca2Ru1-xFexO4
(0<x<0.20) as functions of temperature, magnetic field and pressure. Ca2RuO4 is
a structurally-driven Mott insulator with a metal-insulator (MI) transition at
TMI = 357 K, which is well separated from antiferromagnetic order at TN = 110
K. Fe substitution for Ru in Ca2RuO4 causes a pronounced magnetization reversal
and giant negative volume thermal expansion (NVTE). The magnetization reversal
is a result of a field-induced antiferromagnetic coupling between the Ru- and
Fe-magnetic sublattices that have different temperature dependence. The NVTE is
closely associated with the orthorhombic distortion, and becomes smaller as the
orthorhombicity weakens due to either Fe doping or application of pressure. The
study highlights an intriguing interplay between lattice, orbital and spin
degrees of freedom that is at the root of the novel phenomena in Ca2RuO4.
