Exchange Bias Magnetic Exercise And Recovery Effects Of And The Preparation Of The Gmr Spin Valve

The 2007 Nobel Prize in Physics was awarded to Albert Fert and Peter Griinberg for the discovery of Giant Magnetoresistance (GMR). It highlighted the remarkably rapid crossover of "spintronics" from fundamental studies of spin-dependent transport in metallic ferromagnetic multilayers to a device technology critical to the magnetic storage industry. During the past two decades, extensive experimental and theoretical investigations have been performed on this most exciting and challenging area. This dissertation focuses on the exchange bias which is the fundermental part of spintronic devices and fabrication of GMR spin valve multilayers. The main contents are summarized as follows:In the first part, we mainly investigate the training effect of exchange bias. In NiFe/FeMn bilayers, we have for the first time oberseved and quantified the rotation of pinning direction in its training effect. During consecutive hysteresis loops, the rotation of the pinning direction strongly depends on magnetization reversal mechanism of ferromagnet layer. The rotation of the pinning direction is the physical origin of training effect. In FeCr/IrMn bilayers, we have demonstrated the correlation between training effect and magnetization reversal mechanism by adjusting the composition of FeCr layer as well as its magnetization reversal mechanism. Both the conventional and anomalous training effect have been observed.In the second part, we investigate the hysteretic behavior of angular dependence of exchange bias and the recovery effect of exchange bias together with the rotated pinning direction. In the hysteresis behavior of angular dependence of exchange bias, not only the HC and HE, the pinning direction has also changed during angular measurements of exchange bias. The rotation of pinning direction explains the hysteresis behavior of angular dependence of exchange bias. In the recovery effect of exchange bias, application of a recovery magnetic field at specific direction can recover the exchange bias. The rotated pinning direction can be used to explain this asymmetric effect. Furthermore, the dependence of the recovery effect on the magnitude and application time of recovery magnetic field has also been investigated.In the third part, we introduce the fabrication of the linear GMR spin valve Si/Ru/IrMn/Co/Ru/Co/Cu/Co/NiFe/Ta. Different from the conventional methods to achive the linearlity of spin valve, we use two different external magnetic field during fabrication to induce orthogonal anisotropies in the free and pinned layers, and successfully fabricate the linear GMR spin valve.