Probing the interplay between lattice dynamics and short-range magnetic correlations in CuGeO3 with femtosecond RIXS

E Paris,R Saint-Martin,S Johnston,A Revcolevschi,M Rumo,T Schmitt,G Coslovich,C Monney,A Kemper,M F Lin,W Schlotter,Y Tseng,S Zohar,C W Nicholson,G L Dakovski,V N Strocov

doi:10.1038/s41535-021-00350-5

Abstract

Investigations of magnetically ordered phases on the femtosecond timescale have provided significant insights into the influence of charge and lattice degrees of freedom on the magnetic sub-system. However, short-range magnetic correlations occurring in the absence of long-range order, for example in spin-frustrated systems, are inaccessible to many ultrafast techniques. Here, we show how time-resolved resonant inelastic X-ray scattering (trRIXS) is capable of probing such short-ranged magnetic dynamics in a charge-transfer insulator through the detection of a Zhang–Rice singlet exciton. Utilizing trRIXS measurements at the O K-edge, and in combination with model calculations, we probe the short-range spin correlations in the frustrated spin chain material CuGeO3 following photo-excitation, revealing a strong coupling between the local lattice and spin sub-systems.

Highlights

Among the family of transition metal oxides, the charge-transfer materials are highly studied due to the realization of a number of exotic properties, from metal-insulator transitions to high-Tc superconductivity
We explore the effect of lattice dynamics on the short-range spin correlations in a frustrated low–dimensional spin system and set the stage for future investigations of these interactions exploiting next-generation X-ray free-electron lasers (FELs) sources
The energy of the FEL X-ray pulses is tuned to the O K-edge (~531 eV) and set to be resonant to an absorption peak sensitive to the upper Hubbard band (UHB) electrons[35]

Summary

Introduction

Among the family of transition metal oxides, the charge-transfer materials are highly studied due to the realization of a number of exotic properties, from metal-insulator transitions to high-Tc superconductivity These phenomena often arise from the microscopic coupling between charge, spin, orbital, and lattice degrees of freedom. In this regard, a significant advancement in understanding the origin of these exotic properties may be obtained by employing ultrafast time-resolved techniques to probe the dynamics of the relevant ordered phases. When materials crystallize in a purely one-dimensional (1D) crystal structure they cannot support longrange magnetic order[11], even in the presence of strong short-range magnetic correlations Such correlations are not accessible to many ultrafast techniques such as time-resolved photoemission, Xray diffraction, or optical spectroscopies. The advent of the nextgeneration FELs worldwide is expected to overcome these limitations, enabling the study of a wide class of problems in condensed matter and beyond

Methods

Results

Conclusion