data storage; switching; XMCD; vortex; PolLux; Swiss Light Source; Paul Scherrer Institut; thin film; permalloy; electron beam lithography; genetic algorithm; magnetism; nano-scale materials; x-rays; data storage; microscopy; materials science
Pilet Nicolas, Lisunova Yuliya, Lamattina Fabio, Stevenson Stephanie E., Pigozzi Giancarlo, Paruch Patrycja, Fink Rainer H., Hug Hans J., Quitmann Christoph, Raabe Joerg (2016), A single probe for imaging photons, electrons and physical forces, in NANOTECHNOLOGY
, 27(23), 235705.
Wohlhueter Phillip, Bryan Matthew Thomas, Warnicke Peter, Gliga Sebastian, Stevenson Stephanie Elizabeth, Heldt Georg, Saharan Lalita, Suszka Anna Kinga, Moutafis Christoforos, Chopdekar Rajesh Vilas, Raabe Joreg, Thomson Thomas, Hrkac Gino, Heyderman Laura Jane (2015), Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems, in NATURE COMMUNICATIONS
, 6, 7836.
Heldt Georg, Bryan Matthew T., Hrkac Gino, Stevenson Stephanie E., Chopdekar Rajesh V., Raabe Joerg, Thomson Thomas, Heyderman Laura J. (2014), Topologically confined vortex oscillations in hybrid [Co/Pd](8)-Permalloy structures, in APPLIED PHYSICS LETTERS
, 104(18), 182401.
Stevenson S.E., Moutafis C., Heldt G., Chopdekar R.V., Quitmann C., Heyderman L. J., Raabe J. (2013), Dynamic stabilization of nonequilibrium domain configurations in magnetic squares with high amplitude excitations, in PHYSICAL REVIEW B
, 87(5), 054423.
Wintz S, Strache T, Korner M, Fritzsche M, Marko D, Monch I, Mattheis R, Raabe J, Quitmann C, McCord J, Erbe A, Fassbender J (2011), Direct observation of antiferromagnetically oriented spin vortex states in magnetic multilayer elements, in APPLIED PHYSICS LETTERS
, 98(23), 232511-232511.
Pilet Nicolas, Raabe Joerg, Stevenson Stephanie E., Romer Sara, Bernard Laetitia, McNeill Christopher R., Fink Rainer H., Hug Hans J., Quitmann Christoph, Nanostructure characterization by a combined x-ray absorption / scanning force microscopy system, in Nanotechnology
, 23(47), 475708.
Magnetic structures with micron and sub-micron dimensions have properties different from anything we know in the macroscopic world. Because their dimensions are larger but comparable to the quantum mechanical exchange length, their magnetic configuration is simple and can fully be controlled by their size, shape and material: they are mesoscopic.Such particles are the basis for modern data storage in the computer industry. In each write step their configuration is switched from one stable state (1) to another (0). Switching of the magnetization is a non-linear and potentially chaotic process; the details and the underlying mechanisms are poorly understood and hotly debated in the literature.We suggest using x-ray microscopy to image the switching process with sub-micron spatial and sub-nanosecond temporal resolution. We will first identify magnetic eigenmodes of the mesoscopic structures. To switch the magnetization we will then resonantly (sine wave) excite such modes, a subsequent short field burst (single or few cycle pulse) will then induce switching.Our understanding of the physics of such mesoscopic magnetic structures and their eigenmodes will allow optimization of the switching in terms of speed and energy consumption as well as long term stability. The experiments will be accompanied by micromagnetic simulations helping to interpret the results.We request funding for a PhD student. The student will become part of the team already working successfully on magnetization dynamics at the Swiss Light Source (SLS). He/she will collaborate with specialists in nano-fabrication at Paul Scherrer Institut (PSI) and with colleagues preparing samples in different collaborating universities. The academic host institution will be ETH-Zürich.For the generation of switching pulses of arbitrary shape and duration we request funding of an arbitrary waveform generator (bandwidth >7.5 GHz).The emphasis of the project is on understanding the dynamics of mesoscopic magnetic structures, but it may as well produce know-how for applications. Initially conventional materials like permalloy will be used, because these provide extremely well controllable magnetic properties and can be switched reproducibly. Once proven successful, the project can be extended to more advanced materials and effects like spin torque switching. Furthermore, the question lends itself to application of advanced optimization methods like genetic algorithms, allowing optimization in complex multi parameter space.The investigations will profit from the planned performance upgrade of the SLS and ongoing improvements in x-ray optics which will provide ~10 ps temporal resolution (low alpha-mode) and sub 10 nm spatial resolution in the near future.