Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 27: CE: Poster Session
TT 27.16: Poster
Wednesday, March 24, 2010, 14:00–18:00, Poster D1
Low-T magnetic phase diagram of Yb(Rh0.73Co0.27)2Si2 — •Stefan Lausberg1, Christoph Klingner2, Cornelius Krellner1, Manuel Brando1, Christoph Geibel1, and Frank Steglich1 — 1Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany — 2Physics Department E14, TU München, James-Franck Str., 85748 Garching, Germany
The heavy fermion system YbRh2Si2 is situated close to a quantum critical point. At TN = 70 mK it shows a transition to an antiferromagnetic (AFM) phase. Under pressure TN increases and a second AFM phase emerges at a temperature TL < TN. Both phases persist up to 8 GPa [2]. Isoelectronic substitution of Rh by Co leads to a similar effect as pressure, apart from the fact that at a Co concentration of 27 % both transition temperatures seem to merge [3].
In this contribution we present low-temperature ac-susceptibility χ′(T,H) and resistivity ρ(T,H) measurements of high-quality single crystals of Yb(Rh0.73Co0.27)2Si2. We observe just a single magnetic transition in zero field down to 20 mK, which is of the 2nd order. Increasing the field TN is suppressed at about µ0Hc≈ 0.53 T where the phase boundary line drops very rapidly. This suggests that the phase line could become 1st order although no hysteresis is seen at Hc. Furthermore we observe Fermi liquid behavior around the critical field and within the AFM phase.
[1] S. Mederle et al., JMMM 226-230 (2001) 254-255
[2] G. Knebel et al., JPSJ 75 (2006) 114709
[3] C. Klingner, Diploma Thesis (2009), Dresden.