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TT: Fachverband Tiefe Temperaturen

TT 19: Correlated Electrons: Quantum-Critical Phenomena

TT 19.4: Vortrag

Dienstag, 26. Februar 2008, 14:45–15:00, H 3010

Low Temperature Investigations of YbRh₂Si₂ doped with Ir and Co — •Tanja Westerkamp¹, Philipp Gegenwart², Cornelius Krellner¹, Christoph Geibel¹, and Frank Steglich¹ — ¹Max-PIanck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — ²1. Physikalisches Institut, Georg-August-Universität, Göttingen, Germany

The tetragonal heavy fermion system YbRh₂Si₂ shows interesting properties due to its vicinity to an antiferromagnetic quantum critical point (QCP). At zero magnetic field the system becomes antiferromagnetic below T_N=70 mK. The system can be tuned through a field-induced QCP at B_c=0.05 T into a Landau-Fermi liquid (LFL) state at B>B_c. This state is restricted to temperatures below a scale T_LFL(B). Recently, an additional energy scale T^*(B) was found that vanishes at the QCP and was related to the disintegration of the heavy quasiparticles.

We studied the effect of chemical pressure on the phase diagram, using high quality Yb(Rh_1−xM_x)₂Si₂ single crystals with M = Ir,Co. Here, we present recent results focusing on measurements of the magnetic susceptibility.