50 year old mystery finally solved!

An international team of researchers, including Darren Peets and Tobias Ritschel of the IFMP, has resolved the origin of a mysterious phase transition in the layered perovskite Sr₃Fe₂O₇. Although first evidence for electronic order in Sr₃Fe₂O₇ has been reported more than fifty years ago, all attempts to elucidate the microscopic structure of that order failed. In the present study, the researchers employed cutting-edge neutron and X-ray diffraction methods to search for this "hidden order". The breakthrough was finally achieved by means resonant X-ray diffraction, which enabled to detect the spontaneous formation of a checkerboard-type electronic order.

original publication: Phys. Rev. Lett. 127, 097203 (2021)