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HL: Halbleiterphysik

HL 13: Spin controlled transport I

HL 13.9: Talk

Tuesday, March 28, 2006, 13:00–13:15, BEY 118

Magnetic anisotropy and antiferromagnetic exchange of Co impurities in ZnO — •Roland Hayn¹, Pascal Sati¹, Anatole Stepanov¹, Roman Kuzian², Thomas Chanier¹, Steffen Schäfer¹, Sonia Régnier¹, and Christian Morhain³ — ¹Laboratoire Materiaux et Microelectronique de Provence, 13397, Marseille Cedex 20, France — ²Institute for Material Science, Krzhizhanovskogo 3, 03180 Kiev, Ukraine — ³Centre de Recherche sur l’Hetero-Epitaxie et ses Applications-CNRS, 06560, Valbonne Sophia-Antipolis, France

We report on the magnetic properties of (Zn,Co)O epitaxial thin films with low Co concentration. Magnetic and EPR measurements, combined with crystal field theory, reveal that isolated Co impurities possess a strong single ion anisotropy, which would lead to an easy plane ferromagnetic state when a hypothetical Co-Co interaction would be considered. However, the magnetization measurements show the presence of short-range antiferromagnetic exchange interactions between nearest-neighbor magnetic ions which is supported by LSDA+U calculations.