Tutorial 7

Aim: Understanding (tunneling) magnetoresistance, its connection to the DOS of the ferromagnetic electrodes and how it is influenced by voltage bias and spacer properties.

Manuscripts to be discussed:

• De Teresa et al., 1999: Inverse Tunnel Magnetoresistance in Co/SrTiO₃/La_0.7Sr_0.3MnO₃
• De Teresa et al., 1999: Role of Metal-Oxide Interface in Determining the Spin Polarization of Magnetic Tunnel Junctions
• Xiong et al., 2004: Giant magnetoresistance in organic spin-valves

Guiding questions:

• What is meant by electron spin polarization? What is the physics picture behind it?
• Why is an inverse tunnel magnetoresistance expected for Co electrodes in a Co/SrTiO₃/La_0.7Sr_0.3MnO₃ junction?
• How is a normal tunnel magnetoresistance explained for Al₂O₃ barriers?
• How is the tunneling model extended to describe the behavior of the organic spin valve by Xiong et al.? (focus on p. 823f, not fig.1c)