Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userQuantitative study of valence and configuration interaction parameters of the Kondo semiconductors CeM2Al10 (M = Ru, Os and Fe) by means of bulk-sensitive hard x-ray photoelectron spectroscopy
128
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The occupancy of the 4f^n contributions in the Kondo semiconductors CeM2Al10(M = Ru, Os and Fe) has been quantitatively determined by means of bulk-sensitive hard x-ray photoelectron spectroscopy (HAXPES) on the Ce 3d core levels. Combining a configuration interaction scheme with full multiplet calculations allowed to accurately describe the HAXPES data despite the presence of strong plasmon excitations in the spectra. The configuration interaction parameters obtained from this analysis -- in particular the hybridization strength V_eff and the effective f binding energy Delta_f -- indicate a slightly stronger exchange interaction in CeOs2Al10 compared to CeRu2Al10, and a significant increase in CeFe2Al10. This verifies the coexistence of a substantial amount of Kondo screening with magnetic order and places the entire CeM2Al10 family in the region of strong exchange interactions.
rate research
Read More
We have performed a photoemission spectroscopy (PES) study of CeM2Al10 (M = Fe, Ru, and Os) to directly observe the electronic structure involved in the unusual magnetic ordering. Soft X-ray resonant (SXR) PES provides spectroscopic evidence of the hybridization between conduction and Ce 4f electrons (c-f hybridization) and the order of the hybridization strength (Ru < Os < Fe). High-resolution (HR) PES of CeRu2Al10 and CeOs2Al10, as compared with that of CeFe2Al10, identifies two structures that can be ascribed to structures induced by the c-f hybridization and the antiferromagnetic ordering, respectively. Although the c-f hybridization-induced structure is a depletion of the spectral intensity (pseudogap) around the Fermi level (EF) with an energy scale of 20-30 meV, the structure related to the antiferromagnetic ordering is observed as a shoulder at approximately 10-11 meV within the pseudogap. The energies of the shoulder structures of CeRu2Al10 and CeOs2Al10 are approximately half of the optical gap (20 meV), indicating that EF is located at the midpoint of the gap.
Bulk sensitive hard x-ray photoelectron spectroscopy data of the Ce 3$p$ core level of CeRu$_4$Sn$_6$ are presented. Using a combination of full multiplet and configuration iteration model we were able to obtain an accurate lineshape analysis of the data, thereby taking into account correlations for the strong plasmon intensities. We conclude that CeRu$_4$Sn$_6$ is a moderately mixed valence compound with a weight of 8% for the Ce $f^0$ configuration in the ground state.
We have carried out bulk-sensitive hard x-ray photoelectron spectroscopy (HAXPES) measurements on in-situ cleaved and ex-situ polished SmB6 single crystals. Using the multiplet-structure in the Sm 3d core level spectra, we determined reliably that the valence of Sm in bulk SmB6 is close to 2.55 at ~5 K. Temperature dependent measurements revealed that the Sm valence gradually increases to 2.64 at 300 K. From a detailed line shape analysis we can clearly observe that not only the J=0 but also the J=1 state of the Sm 4f 6 configuration becomes occupied at elevated temperatures. Making use of the polarization dependence, we were able to identify and extract the Sm 4f spectral weight of the bulk material. Finally, we revealed that the oxidized or chemically damaged surface region of the ex-situ polished SmB6 single crystal is surprisingly thin, about 1 nm only.
SmO thin film is a new Kondo system showing a resistivity upturn around 10 K and was theoretically proposed to have a topologically nontrivial band structure. We have performed hard x-ray and soft x-ray photoemission spectroscopy to elucidate the electronic structure of SmO. From the Sm 3$d$ core-level spectra, we have estimated the valence of Sm to be $sim$2.96, proving that the Sm has a mixed valence. The valence-band photoemission spectra exhibit a clear Fermi edge originating from the Sm 5$d$-derived band. The present finding is consistent with the theory suggesting a possible topological state in SmO and show that rare-earth monoxides or their heterostructures can be a new playground for the interplay of strong electron correlation and spin-orbit coupling.
Non-centrosymmetric EuTGe3 (T=Co, Ni, Rh, and Ir) possesses magnetic Eu2+ ions and antiferromagnetic ordering appears at low temperatures. Transition metal substitution leads to changes of the unit cell volume and of the magnetic ordering. However, the magnetic ordering temperature does not scale with the volume change and the Eu valence is expected to remain divalent. Here we study the bulk electronic structure of non-centrosymmetric EuTGe3 (T=Co, Ni, Rh, and Ir) by hard x-ray photoelectron spectroscopy. The Eu 3d core level spectrum confirms the robust Eu2+ valence state against the transition metal substitution with a small contribution from Eu3+. The estimated Eu mean-valence is around 2.1 in these compounds as confirmed by multiplet calculations. In contrast, the Ge 2p spectrum shifts to higher binding energy upon changing the transition metal from 3d to 4d to 5d elements, hinting of a change in the Ge-T bonding strength. The valence bands of the different compounds are found to be well reproduced by ab initio band structure calculations.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
