First RIXS study of a magnetic superstructure in underdoped YBa2Cu3O7-δ

Recently a polarized neutron diffraction (PND) experiment has unveiled, in underdoped YBa2Cu3O7-x (YBCO), a new type of order associated to a hidden lattice translational-breaking intra-unit-cell magnetism and apparently related to the pseudogap state. In an exploratory Cu L3 RIXS experiment we have found the signature of the same order. We propose therefore to study this phenomenon with RIXS in YBCO single crystals and thin films, so to make the bridge with neutron results. The doping, temperature and magnetic field evolution will tell us how strict correspondence is between the peaks measured by the two techniques. Ultimately, the experiment will enable the study of intra-unit-cell magnetism in thin films, a domain which is inaccessible to neutron experiments, where strain and sample confinement can provide decisive information about the importance of this phenomenon in the physics of cuprate HTS.