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MA: Magnetismus

MA 5: Spinstrukturen und magnetische Phasenüberg
änge

MA 5.3: Vortrag

Freitag, 4. März 2005, 11:00–11:15, TU EMH225

Spin reorientation in high magnetic field and the Co-Gd exchange field in GdCo₅ — •Michael Kuzmin¹, Yuri Skourski¹, Dieter Eckert¹, Manuel Richter¹, Karl-Hartmut Müller¹, Konstantin Skokov², and Irina Tereshina³ — ¹Leibniz-Institut für Festkörper- und Werkstoffforschung, IFW Dresden, PF 270116, D-01171 Dresden — ²Faculty of Physics, Tver State University, 33 Gelabova Str., 170002 Tver, Russia — ³Baikov Institute of Metallurgy and Materials Science RAS, Leninskii Pr. 49, 119991 Moscow, Russia

An upturn in the high-field magnetization curve of a GdCo₅ single crystal is observed at about 46 T, which is interpreted as the onset of a process of spin reorientation from the ferri- towards ferromagnetic structure via an intermediate canted phase. This enables us to evaluate the Co-Gd exchange field in GdCo₅ as B_TR=233 ± 12 T. This value is very close to the total exchange field on Gd, B_R= 236 ± 8 T, known from earlier inelastic neutron experiments. The difference, B_RR = B_R − B_TR, is attributed to the Gd-Gd exchange interaction. Its smallness provides solid experimental justification for neglecting the 4f-4f exchange in 3d-4f hard magnetic materials. A full-potential density-fuctional calculation of B_TR has been carried out using a new approach within the fixed-spin-moment (FSM) technique. The calculated value, B_TR = 258 T, is 11% too high, most likely because the FSM formalism disregards orbital magnetic moments.