Magnetic frustration in an iron-based Cairo pentagonal lattice - Ressouche, Eric (Commissariat à l'Énergie Atomique et aux Énergies Alternatives (França)) ; Simonet, V. (Institut Néel (Grenoble, França)) ; Canals, B. (Institut Néel (Grenoble, França)) ; Gospodinov, M. (Bulgarian Academy of Sciences. Institute of Solid State Physics) ; Skumryev, Vassil (Universitat Autònoma de Barcelona. Departament de Física) ; American Physical Society