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MA: Fachverband Magnetismus

MA 27: Spin Structures and Magnetic Phase Transitions

MA 27.3: Vortrag

Donnerstag, 25. März 2010, 17:45–18:00, H10

Weak random anisotropy in the two-dimensional limit - FeZr-based thin films and multilayers — •Andreas Liebig¹, Panagiotis Korelis², Gabriella Andersson², Manfred Albrecht¹, and Björgvin Hjörvarsson² — ¹Chemnitz University of Technology, Institute of Physics, Chemnitz, Germany — ²Dept. of Physics and Material Sciences, Uppsala University, Uppsala, Sweden

We present a study on the magnetic properties of Fe₉₀Zr ₁₀/Al₇₀Zr₃₀ amorphous multilayers, based on MOKE and SQUID magnetometry. Fe₉₀Zr₁₀ is an archetypical example for a reentrant ferromagnet, exhibiting spin glass phase at low temperatures and a ferromagnetic phase at intermediate temperatures.

From structural and magnetic measurements we could ensure the absence of a crystalline phase, and interlayer thicknesses of 4.5 nm yielded negligible interlayer exchange coupling. The amorphous layers can therefore be treated as magnetically decoupled, besides dipolar interactions. Consequently, the ordering temperature scales with the thickness of the magnetic layers. Furthermore, the finite thickness influences the character of the phase transition itself. For the low-temperature limit the spin-glass phase is suppressed. Above the apparent ferromagnetic ordering temperature a phase with exceedingly high magnetic susceptibility is found. Similarities with the random anisotropy two-dimensional X-Y model are discussed.