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TT: Fachverband Tiefe Temperaturen

TT 9: Poster Session: Correlated Electrons

TT 9.3: Poster

Dienstag, 28. September 2021, 13:30–16:00, P

Probing the electron-lattice coupling near the valence transition of EuPd₂Si₂ — •Jan Zimmermann, Steffi Hartmann, Bernd Wolf, Marius Peters, Cornelius Krellner, and Michael Lang — PI, SFB/TR288, Goethe Univ., Frankfurt/M., Deutschland

The thermodynamic properties of materials close to a second-order critical endpoint in strongly correlated electron systems are a field of high interest. Within the strong-coupling regime, it is expect to find cross-correlations between electronic and lattice properties like the recently proposed phenomena of critical elasticity, which implies a strong lattice softening and strongly nonlinear strain-stress relations. [1] Intermetallic compounds from the EuT₂X₂ family show various types of phase transitions such as valence- or structural instabilities that make it possible to study collective phenomena resulting from such a particularly strong coupling of electrons to phonons [2]. In this work electron lattice coupling near the second-order critical endpoint of the valence transition in EuPd₂Si₂ is investigated via thermodynamic methods. Recently published measurements [2] indicate the unique possibility of experimental access to the critical endpoint of the valence transition using helium gas pressure. We present measurements of thermal expansion and compressibility in a pressure range from 0 MPa up to 40 MPa and temperatures from 90 K to 210 K. Results are compared to specific heat measurements and analyzed for sample-to-sample variations.
[1] E. Gati et al., Sci. Adv. 2, e1601646 (2016)
[2] Y. Onuki et al., Philosophical Magazine 97, 3399 (2017)