講演題目: Hidden Charge Order and Magnetic States in Square-Lattice Sr3Fe2O7
講師: Darren Peets 氏 (Technische Universitat Dresden)
日時: 2022年11月4日（金）16:30-18:00
場所: 北海道大学理学部5号館5-205
要旨:
Since the discovery of charge disproportionation in the FeO2 square-lattice compound Sr3Fe2O7 by Mössbauer spectroscopy more than fifty years ago, the spatial ordering pattern of the disproportionated charges has remained “hidden” to conventional diffraction probes, despite numerous x-ray and neutron scattering studies. We have used neutron Larmor diffraction and Fe K-edge resonant x-ray scattering to demonstrate checkerboard charge order in the FeO2 planes that vanishes at a sharp second-order phase transition upon heating above 332 K. Stacking disorder of the checkerboard pattern due to frustrated interlayer interactions broadens the corresponding superstructure reflections and greatly reduces their amplitude, thus explaining the difficulty to detect them by conventional probes. I will discuss implications of these findings for research on “hidden order” in other materials and also discuss some novel multiple-q magnetic structures we have identified in Sr3Fe2O7.
世話人：井原慶彦
（北海道大学大学院理学研究院物理学部門）