Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 4: Magnetic Coupling Phenomena; Exchange Bias

MA 4.5: Talk

Monday, February 25, 2008, 11:15–11:30, H 1028

Exchange coupling between an amorphous ferromagnet and a crystalline antiferromagnet — •Marian Fecioru-Morariu¹, Manfred Rührig², Alessio Lamperti³, Brian Tanner³, and Gernot Güntherodt¹ — ¹Physikalisches Institut (IIA), RWTH Aachen University, 52056 Aachen, Germany — ²SIEMENS AG, Corporate Technology, CT MM 1, Innovative Electronics, 91052 Erlangen, Germany — ³University of Durham, Durham DH1 3LE United Kingdom

We have investigated the exchange bias (EB) effect in bilayers of an amorphous ferromagnet (CoFeB) and a crystalline antiferromagnet (IrMn) in a top-pinned configuration [1]. When the crystalline IrMn layer was deposited on top of the amorphous CoFeB layer, no EB was observed. Upon insertion of a thin crystalline ferromagnetic layer of NiFe between the amorphous CoFeB and the crystalline IrMn, EB appeared and it depended on the thickness of the NiFe layer. An enhancement of the blocking temperature of the CoFeB/NiFe/IrMn layers was observed upon increasing the thickness of the NiFe layer. These effects were directly correlated with the (111) texture in the antiferromagnetic phase of the IrMn layer, which developed progressively with increasing thickness of the NiFe layer. Such a NiFe interlayer can be used to introduce an additional source of anisotropy in a GMR sensor, by exchange coupling the free FM layer of CoFeB in an orthogonal direction to the anisotropy direction of the pinned FM layer of the GMR sensor. // The support through the EU RTN NEXBIAS (HPRN-CT-2002-00296) is acknowledged. [1] M. Fecioru-Morariu, et al., J. Appl. Phys. 102, 053911 (2007).