SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 4: f-Electron Systems and Heavy Fermions I

TT 4.8: Vortrag

Montag, 27. März 2023, 11:30–11:45, HSZ 201

Tuning the ground state of EuPd₂(Si_1−xGe_x)₂ using He-gas pressure — •Bernd Wolf, Theresa Lundbeck, Marius Peters, Kristin Kliemt, Cornelius Krellner, and Michael Lang — Physikalisches Institut, Goethe University, 60438 Frankfurt/Main, Germany

The strongly correlated intermetallic compound EuPd₂Si₂ shows a strong valence-change crossover in a small temperature range. This valence change is accompanied by pronounced lattice effects together with significant changes in the magnetic properties. The material is located on the high-pressure side (crossover range) of the second-order critical endpoint (CEP) where novel collective phenomena which originate from a particularly strong coupling between electronic-, magnetic- and lattice degrees of freedom can be expected. We present magnetic susceptibility measurements data taken on high-quality single crystals of EuPd₂(Si_1−xGe_x)₂ for nominal Ge-concentrations 0 ≤ x_nom ≤ 0.2 in the temperature range 2 K ≤ T ≤ 300 K and He-gas pressure up to 0.5 GPa. For x = 0 at ambient pressure we observe a pronounced valence crossover centered around T_V ∼ 160 K. As expected, T_V shifts to lower temperatures with increasing Ge-concentration, reaching T_V ∼ 90 K for x_nom = 0.1, while still showing a non-magnetic ground state. For x_nom = 0.2 we observe long-range antiferromagnetic order setting in below T_N = 47.3 K. The important finding is that the application of a weak pressure as low as 0.2 GPa the long-range magnetic order can be suppressed giving way to a non-magnetic ground state with pronounced valence fluctuations.