Electronic structure of CeRhX (X = Sn, In)

Abstract

Abstract. Electronic structure of the compounds CeRhIn and CeRhSn have been studied by the X-ray photoemission spectroscopy (XPS) and ab initio band structure calculations. CeRhSn shows the non-Fermi liquid characteristics at low temperatures, while CeRhIn exhibits a Fermi-liquid ground state. At ambient temperature the XPS data reveal an intermediate valence state of Ce ions in both systems. The Ce corelevel XPS spectra are very similar and indicate the strong coupling of the Ce 4f and the conduction band states (Δ ≈ 100 meV). The valence band spectra we interpret with the help of ab initio calculations as well as using the results for the reference compounds LaRhIn and LaRhSn. The comparative analysis of the theoretical band structures and charge density plots reveal the changes in chemical bonding and the hybridization between the Ce 4f and the other valence states introduced by the replacement of In by Sn atoms. The more covalent character of the chemical bonding in the stannides is in line with the smaller thermal expansion. Finally, for CeRhIn we found a typical temperature dependence of the crystal lattice, while CeRhSn shows distinct anomaly at about 120 K, presumably related to the change in planar Ce-Rh bonds.PACS. 79.60.-i Photoemission and photoelectron spectra -71.20.LP Intermetallic compounds -71.27.+a Strongly correlated electron systems; heavy fermions

Coexistence of magnetic order and valence fluctuations in the Kondo lattice systemCe2Rh3Sn5

“…The obtained ∆ value is comparable to those found in systems with Ce in an IV state (∆ 100 meV) 26,27,42 and is notably stronger than in other compounds from the ternary Ce-Rh-Sn system with trivalent Ce ions (∆ 80 meV) 20,[22][23][24][25] . In particular, the ∆ value for Ce 2 Rh 3 Sn 5 is larger than that for the structurally related compound CeRh 2 Sn 4 with Ce 3+ , as evidenced directly by larger intensities of f 2 satellites in the Ce 3d XPS spectra (see Fig.…”

“…Such extraordinarily short Ce2-Rh contacts indicate that the valence of Ce2 ions should be larger than +3. 6,27,42,43 In turn, for Ce1 ions all the Ce1-Sn and Ce1-Rh distances are nearly equal to the sum of corresponding atomic radii. This suggests that the electronic configuration for Ce1 ions is close to 4f 1 , i.e.…”

“…[20][21][22][23] In contrast, for Ce 3+x Rh 4 Sn 13−x (0.2 x 0.6) no sign of Kondo effect or long range magnetic order was found even down to 0.4 K. 25 In turn, in CeRhSn the Ce ions are in an IV state. 26,27 Here, we report on Ce 2 Rh 3 Sn 5 that crystallizes in the orthorhombic Y 2 Rh 3 Sn 5 type of structure, where Y ions occupy two distinct crystallographic sites. 28,29 An early study revealed a moderate HF behaviour (γ ≈ 150 mJ Ce-mol −1 K −2 ) with a magnetic transition at T N ≈ 5 K (from resistivity), 4 K (from magnetic susceptibility) or 2.5 K (from heat capacity).…”

“…We focused our search on the system Ce-Rh-Sn as it is rich in ternary phases that show a full spectrum of strongly correlated electron phenomena related to various strength of hybridization between Ce 4f and other valence band states. [20][21][22][23][24][25][26][27] CeRhSn 2 , Ce 5 Rh 4 Sn 10 , CeRh 2 Sn 4 and Ce 3 Rh 4 Sn 13 are magnetically ordered Kondo lattice systems. [20][21][22][23] In contrast, for Ce 3+x Rh 4 Sn 13−x (0.2 x 0.6) no sign of Kondo effect or long range magnetic order was found even down to 0.4 K. 25 In turn, in CeRhSn the Ce ions are in an IV state.…”

Studies of electronic structure across a quantum phase transition in CeRhSb1−xSnx

“…Indeed, DFT calculations properly reproduced experimental value of critical Sn concentration (x c =0.13) and it was testified that atomic disorder is not a necessary factor for the formation of QCP. However, such a disorder leads to the Griffiths phase, which was evidenced for CeRhSn [13,14,20,27]. The schematic phase diagram of CeRhSb 1−x Sn x system in T − x plane has been proposed so far [9].…”