Hexagonal and square arrays of coupled nanomagnets display novel behaviour that arises from frustration, which is the inability to satisfy all interactions simultaneously [1]. We employ synchrotron x-ray photoemission electron microscopy (PEEM) to obtain high contrast images of the magnetic configurations, and also use other large-scale facility techniques such x-ray resonant magnetic scattering, which can give important insights into the magnetic correlations [2]. We have demonstrated the existence of emergent magnetic monopoles [3] and have established a method to create thermally active artificial spin ice with fluctuating magnetic moments, observing the evolution of the magnetic configurations with time in the PEEM. This allows us to study relaxation processes and provides a controlled route to the lowest-energy state [4, 5, 6].

---

[1] L.J. Heyderman and R.L. Stamps, J. Phys.: Condens. Matter 25, 363201 (2013)
[2] J. Perron, L. Anghinolfi, B. Tudu, N. Jaouen, J.-M. Tonnerre, M. Sacchi, F. Nolting, J. Lüning, and L.J. Heyderman, Phys. Rev. B 88, 214424 (2013) (2013)
[3] E. Mengotti, L.J. Heyderman, A. Fraile Rodríguez, F. Nolting, R.V. Hügli, H.B. Braun Nature Physics 7, 68 (2011)
[4] A. Farhan, P. Derlet, A. Kleibert, A. Balan, R.V. Chopdekar, M. Wyss, L. Anghinolfi, F. Nolting and L.J. Heyderman Nature Physics 9, 375 (2013)
[5] A. Farhan, P.M. Derlet, A. Kleibert, A. Balan, R.V. Chopdekar, M. Wyss, J. Perron, A. Scholl, F. Nolting, and L.J. Heyderman, Phys. Rev. Lett. 111, 057204 (2013)
[6] V. Kapaklis, U.B. Arnalds, A. Farhan, R. V. Chopdekar, A. Balan, A. Scholl, L. J. Heyderman and B. Hjörvarsson, Nature Nanotechnology 9, 514 (2014)

---

Bio

Laura Heyderman began her scientific career in magnetism in 1988, working as a Bristol University PhD student at the CNRS, Paris on magnetic multilayers. As a postdoc at Glasgow University, she performed Lorentz microscopy on a variety of magnetic materials. She then spent four years working in industry in the UK and since 1999, she has been based at the Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute. In January 2013, she became Professor of Mesoscopic Systems at the Department of Materials, ETH Zurich.

Professor Heyderman has over 130 scientific publications, more recently in the field of magnetic nanostructures. Her work on artificial ferroic systems has led to several invited and plenary talks, articles in the German and French equivalents to Scientific American, and to the Paul Scherrer Institute 2011 Thesis Medal for her PhD student. She is Membership Chair as well as member of the Education and Advisory Committees of the IEEE Magnetics Society. She has been a program and advisory committee member of several international conferences on magnetism and was program chair of the Micro- and Nanoengineering Conference (MNE) 2014.