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Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 16: CE: Quantum-Critical Phenomena 1

TT 16.5: Vortrag

Dienstag, 23. März 2010, 15:00–15:15, H19

Tuning the Eu valence in EuPd3Bx by B substitution and pressure - a joint experimental and theoretical study — •Miriam Schmitt1, Roman Gumeniuk1, Andreas Leithe-Jasper1, Walter Schnelle1, Marcus Schmidt1, Angela Trapananti2, Giuliana Aquilanti2, Ulrich Schwarz1, and Helge Rosner11MPI for Chemical Physics of Solids, Dresden, Germany — 2European Synchrotron Radiat Facil, Grenoble, France

Valence changes induced by doping as well as internal or external pressure often lead to quantum critical phenomena. For EuPd3Bx, an isostructural phase transition upon B substitution, attended by a change of its magnetic properties, was predicted by band structure theory [1]. According to our calculational results, the phase transition in EuPd3Bx can be explained by a change of the Eu valence related to a change of the 4f occupation. Upon B insertion, the Eu3+ in EuPd3 changes to Eu2+ in EuPd3Bx (x ≥ 0.2). By applying pressure this effect can be reversed, driving a magnetic Eu2+ to a non magnetic Eu3+ state. To challenge the prediction of the transitions we carried out XRD and XAS measurements for different B contents as well as for a fixed B content under high pressure. To elucidate the origin of the magnetic change, the experimental results are complemented by density functional based ab-initio band structure calculations using the LDA+U approach (to include strong electron correlations of 4f electrons) and the coherent potential approximation (CPA, to describe substitutional disorder).

[1] C. Loison et al., Phys. Rev. B 75, 205135 (2007).

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