Probing Strongly Correlated 4f-Orbital Symmetry of the Ground State in Yb Compounds by Linear Dichroism in Core-Level Photoemission

TL;DR

This paper demonstrates that linear dichroism in core-level photoemission can reveal the strongly correlated 4f-orbital symmetry of the ground state in Yb compounds, providing a new spectroscopic approach to study electronic anisotropy.

Contribution

It introduces a method using polarization-dependent core-level photoemission to determine 4f orbital symmetry in Yb compounds, linking dichroism to crystalline electric field effects.

Findings

Successfully determined 4f ground-state symmetry in YbRh2Si2 and YbCu2Si2.

Established that linear dichroism reflects anisotropic charge distributions due to crystal fields.

Probed excited-state symmetry via temperature-dependent dichroism measurements.

Abstract

We show that the strongly correlated 4f-orbital symmetry of the ground state is revealed by linear dichroism in core-level photoemission spectra as we have discovered for YbRh2Si2 and YbCu2Si2. Theoretical analysis tells us that the linear dichroism reflects the anisotropic charge distributions resulting from crystalline electric field. We have successfully determined the ground-state 4f symmetry for both compounds from the polarization-dependent angle-resolved core-level spectra at a low temperature well below the first excitation energy. The excited-state symmetry is also probed by temperature dependence of the linear dichroism where the high measuring temperatures are of the order of the crystal-field-splitting energies.