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Condensed Matter Seminar: Frustration by design: Artificial Frustrated Magnets

Event Type
190 Engineering Sciences Bldg - corner Goodwin & Springfield 
Apr 12, 2013   1:00 pm  
Prof Peter Schiffer - Dept of Physics & VCR - University of Illinois
Peggy Pennell
Originating Calendar
Physics - Condensed Matter Seminar

Artificial frustrated magnets consist of arrays of lithographically fabricated single-domain ferromagnetic islands, arranged in different geometries such that the magnetostatic interactions between the island moments are frustrated.  Magnetic force microscopy imaging of these arrays allows us to study the accommodation of frustration through the local correlations between the moments as a function of both the strength of the interactions and the geometry of the frustration.  The interactions can be closely mapped onto those of the ‘spin ice’ materials, and allow a detailed analysis of the local correlations in two dimensions.    We have also used these arrays to analyze the process of demagnetization, which is necessary to access low energy collective states in our arrays and in many other magnetic systems.   We have probed a number of different lattice geometries and find both local ordering and disordered states that mimic the low temperature magnetic behavior of spin ice materials. Our results shed light on the nature of magnetism in patterned arrays and provide a rich arena in which to study the physics of frustration.


References:  R. F. Wang  et al. Nature 439, 303 (2006); C. Nisoli et al. Physical Review Letters 98, 217203  (2007) and Physical Review Letters 105, 047205 (2010); X. Ke et al. Physical Review Letters 101, 037205 (2008) and Applied Physics Letters  93 252504 (2008); Li et al. Physical Review B 81, 092406 (2010) and Physical Review B  82, 134407 (2010); Lammert et al. Nature Physics 6, 786 (2010); Zhang et al. Physical Review Letters 107, 117204 (2011) and Physical Review Letters 109, 087201 (2012).


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