Hamburg 2001 – scientific programme
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SYOD: Oxidische Dünnschichten
SYOD 1: Oxidische Dünnschichten
SYOD 1.7: Invited Talk
Thursday, March 29, 2001, 17:30–18:00, J
Exchange coupling in LaFeO3 / Co thin film systems — •Jin Won Seo1,2, Jean Fompeyrine2, Heinz Siegwart2, and Jean-Pierre Locquet2 — 1Institute de Physique, Institut de Physique, Université de Neuchâtel, CH-2000 Neuchâtel, Switzerland — 2IBM Research, Zurich Research Laboratory, CH-8803 Ruschlikon, Switzerland
Antiferromagnetic (AF) materials are essential elements in the current magnetic sensors, where they serve to pin the nearest ferromagnetic (FM) layer into one preferred orientation. This coupling between the spins in the AF and FM layers − also called the exchange bias − determines to a large extent the efficiency and the long-term stability of the giant magnetoresistance ratio, but is still poorly understood. However, a number of experiments and theoretical models have suggested that the exchange bias is correlated with the presence and morphology of AF domains.
The AF orthoferrite LaFeO3 is an interesting model system to explore this correlation, as the easy axis A is uniquely defined along the a-axis of the orthorhombic crystal. Thin films of LaFeO3 have been grown by molecular beam epitaxy on different substrates. The highest exchange bias of 50 Oe was obtained using MgO. Firstly, we study the growth of LaFeO3 thin films and investigate how the parameters, such as growth condition, epitaxial relationship and strain, control the domain size and shape as well as the Néel temperature. Secondly, we explore how the AF domains pin the FM domains leading to exchange coupling and to a higher exchange bias value.