National Synchrotron Light Source Symposium

High Pressure Electronic Properties Investigated by RIXS: From Magnetic Collapse to Quantum Criticality
Jean-Pascal Rueff, CNRS / Synchrotron SOLEIL, France

hosted by Chi-Chang Kao

We report on the investigation of the electronic properties in strongly correlated materials under high pressure (HP) by resonant inelastic x-ray scattering (RIXS). Pressure-induced phenomena may serve as a window to the materials properties at extreme electronic densities. In transition metal oxides, pressure can provoke metal-insulator transitions through the closure of the correlation gap and a collapse of the magnetic state. The latter can be more precisely studied by x-ray emission spectroscopy at the Kbeta emission line which we will show to be a sensitive probe of the 3d spin state. On the other hand in rare earth and actinides, pressure is at the origin of valence instabilities often conjugated with volume collapse transitions. Resonant emission spectroscopy gives a handle on the mixed-valent state, thus providing extremely valuable information about the hybridized nature of the f-electrons, especially when combined with cluster calculations. Extension of this work to HP / low temperature domain will offer the possibility to explore the phase diagram of heavy fermion compounds in the vicinity of the critical pressure. We will briefly review the experimental setup to be developed in that perspective on the GALAXIES beamline at SOLEIL.