Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 16: CE: Quantum-Critical Phenomena 1
TT 16.7: Talk
Tuesday, March 23, 2010, 15:30–15:45, H19
Exploring the magnetocaloric effect in Cs2CuCl4 close to the field-induced quantum-critical point — •Georg Hofmann, Berd Wolf, Sebastian Belz, Natalija Krüger, Franz Ritter, Wolf Assmus, and Michael Lang — Physikalisches Institut, SFB/TR 49, Goethe-University Frankfurt am Main, 60438 Frankfurt am Main, Germany
The compound Cs2CuCl4 is a quasi-2D geometrically frustrated S = 1/2 antiferromagnet which orders antiferromagnetically below TN = 1.6 K. By increasing an external field to Bc ≈ 8.5 T [1], TN is suppressed to zero which marks a field-induced quantum-critical point (QCP). The QCP, although inaccessible by experiment, manifests itself at finite temperature in an unusual sensitiveness of thermodynamic properties on the tuning parameter [2]. In fact, for a field-induced QCP, a diverging magnetocaloric effect (MCE) ΓB = − ( ∂ S / ∂ B )T / C is expected [2, 3]. Here we present measurements of the MCE in the vicinity of Bc for the title compound by using a step-like measuring technique which ensures quasi-adiabatic conditions. Our results reveal incipient divergencies of ΓB upon approaching the QCP both as a function of field and temperature, consistent with the expectations [3].
[1] Radu et al., Phys. Rev. Lett. 95, 127202 (2005).
[2] Zhu et al., Phys. Rev. Lett. 91, 066404 (2003).
[3] Garst et al., Phys. Rev. B 72, 205129 (2005).