Berlin 2024 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 4: f-Electron Systems

TT 4.8: Vortrag

Montag, 18. März 2024, 11:45–12:00, H 3005

Searching for the critical endpoint in the valence-fluctuating Eu(Rh_1−xCo_x)₂Si₂-system — •Franziska Walther, Alexej Kraiker, Kristin Kliemt, and Cornelius Krellner — Physikalisches Institut, Goethe-Universität Frankfurt, 60438 Frankfurt/Main, Germany

In ternary europium-based intermetallic compounds with the ThCr₂Si₂ structure valence fluctuations of the Eu ions and a coupling between lattice and electronic degrees of freedom lead to intriguing phenomena. Under variation of temperature and pressure, it is possible to enforce a valence transition from a magnetic Eu²⁺ to a non-magnetic Eu³⁺ state [1]. EuRh₂Si₂ orders antiferromagnetically below T_N= 24 K in a stable divalent state [2], whereas the isoelectronic compound EuCo₂Si₂ is nearly trivalent und indicates no magnetic ordering [1]. EuRh₂Si₂ can be shifted with pressure towards a first-order valence transition, which is expected to terminate in a second-order critical endpoint (CEP), where critical elasticity may occur [3]. In this study, we aim to approach the CEP by applying chemical pressure through substituting Rh with Co. It turned out, that the crystal growth process due to the high vapour pressure of europium is a real challenge, however, we successfully have grown first single crystals of this series. We report on the growth of Eu(Rh_1−xCo_x)₂Si₂ samples and investigated their physical properties.
[1] Y. Onuki et al., J. Phys. Soc. Jpn. 89, 102001 (2020)
[2] S. Seiro, C. Geibel, J. Phys.: Condens. Matter 26, 046002 (2014)
[3] F. Honda et al J. Phys. Soc. Jpn. 85, 063701 (2016)

Keywords: critical endpoint; valence-fluctuating; valence transition; critical elasticity; crystal growth