Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 74: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 74.14: Vortrag
Mittwoch, 2. April 2014, 18:30–18:45, BEY 81
Irregular 4f1 spin-orbit splitting in collapsed α-cerium — •Jürgen Röhler — Universität zu Köln, 50937 Köln
The J5/2−J7/2 spin-orbit splitting of the 4f1 groundstate manifold in solid cerium
systems is generally close to the value of free ions, ΔSO≃ 3100 K. Inelastic neutron scattering confirmed this for elemental γ-Ce, but not for the collapsed α-phase with strongly increased ΔSO≃ 5300 K [1]. Also α-type Ce-compounds exhibit significantly increased ΔSO. Renormalization of ΔSO in strongly correlated 4f-systems is usually attributed to 4f-c.e. hybridization increasing slightly the mean orbital expectation value <r4f>, hence decreasing ΔSO. In fact in most Kondo-type and mixed valent systems ΔSO is decreased by ≃ −10%, but not in collapsed α-type Ce systems. The apparent deficiency of the Kondo volume collapse model will be adressed. In particular we discuss the significance of 4fn occupation numbers in the framework of a Mott transition within the 4f configuration.
A.P. Murani et al., Phys. Rev. B48, 13981 (1993).