Magnetism in ErCo2 under high pressure - art. no. 054433

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.