We present results of experiments and ab initio calculations focused on the
stability of Co magnetism in ErCo2 exerted to high pressures. In the exper
iments we have studied pressure effects on electrical-resistivity anomalies
in the vicinity of Curie temperature (T-C = 33 K in ambient pressure) that
are intimately related to the formation and ordering of Co itinerant 3d el
ectron moments. The Co magnetism in this material is a consequence of the i
tinerant electron metamagnetism (IEM) induced in a large exchange field app
earing at Te where the localized Er moments order ferromagnetically. At low
er pressures, Te decreases linearly with increasing pressure p (partial der
ivative ln T-C/partial derivativep=0.24 GPa(-1)). Magnetovolume measurement
s under pressure and magnetic-moment calculations performed for reduced lat
tice parameters reveal that also the Co moment decreases with increasing pr
essure. At higher pressures, the T-C vs p dependence strongly deviates from
the initial linear trend and above a critical pressure p(c) approximate to
4 GPa, the T-C becomes nearly pressure independent. To explain this behavi
or we propose a scenario assuming that for p > p(c) the 3d band broadens to
such extent that the projected Co-3d density of states in the vicinity of
EF decreases critically and the Er-Co-Er exchange channel becomes ineffecti
ve to induce the IEM. The Er sublattice then orders at much lower temperatu
re T-C approximate to 13 K, which is determined by the Er-Er interaction ch
annel mediated by conduction electrons. This scenario is corroborated by re
sults of the ab initio calculations that indicate the collapse of IEM in pr
essures above a certain value.