Regensburg 1998 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 15: Postersitzung II: Massive HTSL (1-12), Supraleitung: Anwendungen (13-34), Josephsonkontakte und Kryoelektronik (35-75), Elektronenstruktur und Phononen in HTSL (76-79), Schwere Fermionen, Kondo-Systeme (80-99)

TT 15.85: Poster

Mittwoch, 25. März 1998, 15:00–18:30, D

Non-Fermi-liquid behaviour of CeRu₂Ge₂ at P_c=7 GPa ? — •H. Wilhelm and D. Jaccard — Université de Genève, DPMC, 24 Quai Ernest-Ansermet, CH-1211 Genève 4

We have investigated the effect of pressure on the magnetic order of CeRu₂Ge₂ up to 10 GPa and down to 30 mK by four-point resistivity measurements. Two magnetic phase transitions at T₁=7.40 K and T₂=8.55 K are found at ambient pressure. The former one is the already known Curie temperature [1] and it is very likely that at the latter one the sample enters into an antiferromagnetic modulated phase [2]. T₁ decreases strongly with increasing pressure and seems to vanish around 4 GPa. In contrast to this, T₂ shifts upwards reaching 11 K at 4 GPa and then starts to decrease rapidly below 30 mK at a critical pressure P_c≈ 7 GPa, where the magnetic/non-magnetic transition takes place. The Fermi-liquid law ρ(T)=ρ₀ + AT² can be fitted to the data in the interval 0<T<T_A=300 mK for P>4 GPa. The upper interval boundary T_A increases with pressure up to about 3 K at ≈7 GPa, then decreases and starts to increase again for P>9 GPa. For P>P_c a linear variation of ρ(T) above T_A and up to very high temperature is found. The magnetic phase diagram as well as the validity of the Fermi-liquid law will be discussed.

[1] R. Felten et al. J. Magn. Magn. Mat. 63&64, 383 (1987)

[2] A. Böhm et al. J. Magn. Magn. Mat. 76&77, 150 (1988)