Resonant inelastic x-ray scattering studies of elementary excitations

Abstract

In the past decade, Resonant Inelastic X-ray Scattering (RIXS) has made remarkable progress as a spectroscopic technique. This is a direct result of the availability of highbrilliance synchrotron X-ray radiation sources and of advanced photon detection instrumentation. The technique's unique capability to probe elementary excitations in complex materials by measuring their energy-, momentum-, and polarization-dependence has brought RIXS to the forefront of experimental photon science. We review both the experimental and theoretical RIXS investigations of the past decade, focusing on those determining the low-energy charge, spin, orbital and lattice excitations of solids. We present the fundamentals of RIXS as an experimental method and then review the theoretical state of affairs, its recent developments and discuss the different (approximate) methods to compute the dynamical RIXS response. The last decade's body of experimental RIXS data and its interpretation is surveyed, with an emphasis on RIXS studies of correlated electron systems, especially transition metal compounds. Finally, we discuss the promise that RIXS holds for the near future, particularly in view of the advent of x-ray laser photon sources.

Anisotropic softening of magnetic excitations along the nodal direction in superconducting cuprates

“…The RIXS experiment. RIXS is a second-order optical process that probes chargeneutral single-particle and collective excitations, with charge or spin character 30 . RIXS measurements at the Cu L 3 absorption edge (2p 3/2 -3d; Fig.…”

“…RIXS offers some interesting advantages, such as the possibility of measuring small-volume samples, additional flexibility from polarization control and complementary information from the Cu (single magnons) and O (two magnons) edges 30 . RIXS has enabled a complete mapping of the spin waves in the insulating cuprates.…”

Spin-state studies with XES and RIXS: From static to ultrafast

“…Resonant inelastic X-ray scattering (RIXS) can also gives valuable insights into the electronic structure [10,9,11]. For spin-state transitions the variations of the 3d state energies and populations are substantial.…”

“…Hard X-ray spectroscopies can provide unique insights into the electronic and geometric structure, combined with element-, orbital-, and orientation sensitivity [9,10,11]. These techniques probe the bulk properties of the sample, and are even compatible with extreme conditions due to the large penetration depths [12].…”

Decrease of d -wave pairing strength in spite of the persistence of magnetic excitations in the overdoped Hubbard model

“…We find that similar to the RIXS studies, high-energy magnetic excitations persist into the overdoped regime. However at large momentum transfer, beyond the range observed by RIXS [8], a reduction and hardening of the strength of the spin-fluctuation spectral weight is observed. We discuss the doping dependence of magnetic excitations for different momenta q, segregating regions which promote d-wave pairing (near q = (π, π)), are indifferent to pairing (along the AF zone boundary), and are hurtful to pairing (near zone center).…”