Speaker
Description
In the edge-shared spin-chain CuGeO3, the relation between charge, spin and lattice degrees of freedom, giving rise to the Spin-Peierls transition, is still unclear. In this regard, Resonant Inelastic X-ray Scattering (RIXS) represent a very powerful tool, capable of probing elementary excitations involving different degrees of freedom in a single experiment. Recently, the advent of Free-Electron Laser sources enabled extending these capabilities to the time domain, allowing pump-probe experiments.
In the O K-edge RIXS spectrum of CuGeO3, one of the charge transfer excitations is characterized by a sharp structure associated to the formation of the Zhang-Rice singlet. The probability for such non-local excitation channel depends on the short-range antiferromagnetic (AF) spin correlations between two neighboring CuO4 plaquettes. We use a 266 nm ultrashort laser pump to excite carriers across the charge-transfer gap, removing spin-1/2 holes from the Cu sites and thus perturbing the local spin-correlations. We use O K-edge RIXS to probe the suppression and recovery of the Zhang-Rice singlet excitations, giving insight in the dynamics of the short-range AF magnetic interactions.
| Position | Postdoc |
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