Regensburg 1998 – wissenschaftliches Programm

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AM: Magnetismus

AM 17: Magnetische Phasenübergänge in drei- und niederdimensionalen Strukturen

AM 17.12: Vortrag

Donnerstag, 26. März 1998, 13:00–13:15, H23

Decoupling of the magnetic ordering in Er_1−xY_xCo₂ compounds driven by subsitution and by pressure — •R. Hauser¹, E. Bauer¹, G. Hilscher¹, H. Michor¹, H. Müller¹, M. Rotter¹, A.S. Markosyan², K. Kamishima³, and T. Goto³ — ¹Institut für Experimentalphysik, Technische Universität Wien, Wiedner Hauptstraße 8-10, A-1040 Wien — ²Faculty of Physics, M.V. Lomonosov Moscow State University, 119899 Moscow, Russia — ³Institute for Solid State Physics, University of Tokyo, Tokyo 106, Japan

In ErCo₂ the itinerant d subsystem and the more localized Er sublattice undergo a common magnetic phase transition at T_C=32 K. The first-order phase transition observed at this temperature is related to itinerant electrons metamagnetism (IEM) of the d subsystem driven by the magnetic ordering of the Er sublattice. By employing thermodynamic and resistivity measurements we show a that for a limited range of concentration x_cr<x<x_cr′ and pressure P_cr<P<P_cr′ the itinerant Co sublattices orders magnetically at T_C^Co which is lower than T_C^R of the more localized Er sublattice. This is referred to either to a weakening of the effective molecular field acting on the Co sites, H_fd^Co, by subsititution or the pressure-driven increase of the the critical field, H_cr, neccessary to induce a moment on the Co sites. On further increasing concentration or pressure only the Er sublattice reveals long-range order. Furthermore, a field-induced collapse of the Co as function of both concentration and pressure was observed and is ascribed to inverse IEM.