AVS 63rd International Symposium & Exhibition
    Thin Film Wednesday Sessions
       Session TF+MI-WeA

Invited Paper TF+MI-WeA3
Magnetic Anisotropy and Relaxation in Spintronic Materials

Wednesday, November 9, 2016, 3:00 pm, Room 104E

Session: Thin Films for Magnetic and Optical Applications
Presenter: Claudia Mewes, The University of Alabama
Authors: C. Mewes, The University of Alabama
T. Mewes, The University of Alabama
J. Beik Mohammadi, The University of Alabama
A. Farrar, The University of Alabama
K. Cole, The University of Alabama
Correspondent: Click to Email

Functional materials with optimized properties, such as the magnetic anisotropy and magnetic relaxation rate, are crucial for the next generation of spintronic devices. Therefore technological progress in this area depends heavily on the successful search for new materials as well as on a deeper understanding of the fundamental mechanisms of the magnetic relaxation and the magnetic anisotropy. This talk will focus on different aspects which can influence the magnetic relaxation as well as the magnetic anisotropy within a confined device setting.

For many spintronic applications the use of thin films with perpendicular anisotropy is often essential for the functionality of the device. For example the use of thin films with perpendicular anisotropy in spin transfer torque magnetic random access memories (STT MRAMs) leads to a reduction of the current density needed to switch the device state. In addition to the perpendicular anisotropy it is often crucial to have materials with a low magnetization relaxation rate. Therefore many spintronic applications rely on ultra-thin magnetic films with a low magnetization relaxation in which the perpendicular anisotropy is created through surface anisotropy. This approach is very sensitive to the interface morphology and chemical environment. In this talk I will discuss the effect of spatial fluctuations of the first order perpendicular anisotropy in thin films and its influence on the effective anisotropy for these materials.

Similar to the magnetic anisotropy the magnetic relaxation in thin ferromagnetic films can be affected by neighboring layers. Spin pumping is a well-known contribution that has to be taken into account for practical applications using multilayer structures. More recently a strong unidirectional contribution to the relaxation in exchange bias systems has been observed experimentally. To describe this phenomenon theoretically we use the formalism of an anisotropic Gilbert damping tensor that takes the place of the (scalar) Gilbert damping parameter in the Landau-Lifshitz-Gilbert equation of motion. In this talk I will discuss this approach to study the modified magnetization dynamics under the influence of unidirectional damping.

ACKNOWLEDGMENTS

C.K.A. Mewes acknowledges support by the NSF-CAREER Award No. 1452670, T. Mewes acknowledges support by the NSF-CAREER Award No. 0952929.