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

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.

Revising the 4f symmetry in CeCu2Ge2 : Soft x-ray absorption and hard x-ray photoemission spectroscopy

“…The mixing parameter α 2 , obtained by XAS, successfully explains the magnetic susceptibility. By analyzing the Ce 3d corelevel HAXPES spectra using the same α 2 value [24][25][26], in-plane symmetry of the 4f states is determined as -type 7 , which is consistent with the results obtained from NIXS measurements [19].…”

Evidence for Γ8 Ground-State Symmetry of Cubic YbB12 Probed by Linear Dichroism in Core-Level Photoemission

“…Furthermore, there is another controllable measurement parameter in photoemission, called the "photoelectron detection direction" relative to the single-crystalline axis, in addition to the polarization direction of the excitation light. Indeed, by using LD in 3d core-level HAXPES spectra, the Yb 3+ 4f ground state has been determined for tetragonal YbCu 2 Si 2 and YbRh 2 Si 2 [23]. LD in the core-level HAXPES for cubic Yb compounds is also expected to be observed, as discussed below.…”

Ground State Local 4f Symmetry of CeAgSb2 Probed by Linearly Polarized Hard X-ray Photoemission

“…However, it is insensitive for the in-plane rotational symmetry, which is described by the ± sign of the linear combination of the |± 5 2 ⟩ and |± 3 2 ⟩ states, due to the fundamental limitation of the dipole selection rule in the tetragonal systems. This problem has been overcome by the linearly polarized angle-resolved hard X-ray photoemission (HAXPES) with an additional parameter of the detection direction of the photoelectrons [9][10][11][12][13][14]. This technique works to determine the GS symmetry of tetragonal CeCu 2 Ge 2 , which shows an antiferromagnetic order below a Néel temperature (T N ) of 4.15 K at ambient pressure [15], as |Γ 1 7…”