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MA: Fachverband Magnetismus

MA 18: Poster I : Bio Magn. (1-2); Mag.Imgaging (3-9); Magn. Semiconductors (10-16); Half Metals & Oxides (17-20); Coupl.Phenomena (21-27); Magn. Mat. (28-41); Micro & Nanostr. Magn. Materials (42-61); Micro Magn. (62-64); Surface Magnetism (65-70); Transport Phenomena (71-85)

MA 18.25: Poster

Dienstag, 26. Februar 2008, 15:15–18:30, Poster E

Positive exchange bias in NiFe/IrMn bilayer — •S. K. MISHRA, F. RADU, H. A. DÜRR, and W. EBERHARDT — BESSY GmbH, Albert Einstein Str. 15, D-12489 ,Berlin, Germany

The microscopic origin of the positive exchange bias, i.e. the shift of the ferromagnetic hysteresis in the opposite direction compared to conventional exchange bias, remains elusive.Recently we observed positive exchange bias in a Ni₈₀Fe₂₀/Ir₁₉Mn₈₁ polycrystalline thin-film bilayer system. We have employed soft X-ray Resonant Magnetic Scattering (XRMS) to study element specifically the magnetic properties of the bilayer. After field cooling through the Neel temperature (470K) the system exhibits the conventional negative exchange bias. By training, i.e. repeated magnetization reversals, the positive exchange bias is induced starting at about 420K up to the blocking temperature (450K). This indicates that increasing interfacial magnetic disorder might be the microscopic driving force of the positive exchange bias in the bilayer system.

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References:

[1] F. Radu, M. Etzkorn, R. Siebrecht, T. Schmitte., K. Westerholt, and H. Zabel H. Phys. Rev. B 67, 134409 (2003).

[2] H. Shi, D. Lederman, N. R.Dilley, R. C. Black , J. Diedrichs, K. Jensen, and M.B. Simmonds J. Appl. Phys. 93, 8600-8602 (2003)