Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)
MA 15.134: Poster
Dienstag, 27. März 2007, 15:00–19:00, Poster A
Thermodynamic properties of intermetallic ternary rare-earth compounds — •J. Rohrkamp1, O. Heyer1, H. Hartmann1, T. Lorenz1, J. Mydosh1, R. Pöttgen2, and T. Fickenscher2 — 1II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany — 2Institut für Anorganische und Analytische Chemie, Universität Münster, 48149 Münster, Germany
Ternary rare-earth intermetallics of the composition RETMg with RE=La, Eu, Gd, Yb and T=Ag, Au and GdAuIn show a rich variety of magnetic phases. Depending on the composition these compounds are paramagnetic (RE=La, Yb) or they order either ferro- or antiferromagnetically with transition temperatures ranging from about 13 to 81 K. We measured the susceptibility χ, the resistivity ρ, the specific heat Cp and the thermal expansion coefficient α and found well pronounced anomalies in each quantity at TN or TC. From the measurements of χ and Cp we calculate the magnetocaloric effect, which is sizeable for both the ferro- and the antiferromagnetic compounds. Furthermore we determine the hydrostatic pressure dependencies of the various transition temperatures from the specific heat and thermal expansion data using Ehrenfest’s relation. We find rather large pressure dependencies of the transition temperatures. This indicates that the magnetic ordering is driven by the RKKY interaction between the 4f moments of the rare-earth ions via the conduction electrons.
This work was supported by the DPG through SPP 1166.