Lehmann J. Toroidal Order in Magnetic Metamaterials 2022

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The scope of this work is to provide an extensive experimental investigation of ferrotoroidicity, the most recently established type of ferroic order that is based on the uniform unit-cell-sized alignment of magnetic whirls. This is achieved by transferring basic spin configurations pertinent for the emergence of toroidal order to mesoscopic length scales. An engineering of and access to the system's magnetic degrees of freedom is made possible by using nanomagnetic arrays as model systems. The work reveals microscopic and macroscopic aspects of toroidally ordered matter beyond the reach of natural materials.
Introduction
Scientific Background
Experimental and Computational Methods
Tailoring of the Sample System
Domains in Artificial Magneto-Toroidal Crystals
Poling of Artificial Magneto-Toroidal Crystals
Optical Effects in Artificial Magneto-Toroidal Crystals
Conclusion
Appendix A. Development of Teaching Concepts
Appendix B. Design and Construction of Laboratory Hardware
Appendix C. Additional Experiments on Nanomagnetic Arrays