We developed a method to experimentally quantify the fourth-order multipole moment of the rare-earth 4 f orbital. Linear dichroism (LD) in the Er 3d5=2 core-level photoemission spectra of cubic ErCo2 was measured using bulksensitive hard X-ray photoemission spectroscopy. Theoretical calculation reproduced the observed LD, and the result showed that the observed result does not contradict the suggested 3 8 ground state. Theoretical calculation further showed a linear relationship between the LD size and the size of the fourth-order multipole moment of the Er 3+ ion, which is proportional to the expectation value hO0 4 þ 5O4 4i, where Om n are the Stevens operators. These analyses indicate that the LD in 3d photoemission spectra can be used to quantify the average fourth-order multipole moment of rare-earth atoms in a cubic crystal electric field.
Research Abstract
Research Date
Research Department
Research Journal
Journal of the Physical Society of Japan
Research Member
Research Publisher
Journal of the Physical Society of Japan
Research Vol
87
Research Year
2018
Research Pages
033710