Role of electron correlation and long range magnetic order in the electronic structure of Ca(Sr)RuO₃

Abstract

The room temperature photoemission spectra collected at different surface sensitivities reveal qualitatively different surface and bulk electronic structures in CaRuO₃ and SrRuO₃. The extracted bulk spectra are dominated by the coherent feature intensity with a weak correlation induced feature at higher binding energies. The First principle calculations provide a wonderful representation of the bulk spectra for the effective electron correlation strength, U/W∼0.2 as expected for highly extended 4d systems. This resolves a long-standing issue that arose due to the prediction of large U/W similar to 3d systems. Photoemission spectra across the magnetic phase transition reveal unusual evolution exhibiting a large reduction in the coherent feature intensity in the bulk spectrum of SrRuO₃, while the bulk spectrum in CaRuO₃ remains almost the same down to the lowest temperature studied.