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TT: Fachverband Tiefe Temperaturen

TT 31: Correlated Electrons: Quantum-Critical Phenomena 2

TT 31.4: Vortrag

Mittwoch, 28. März 2012, 15:45–16:00, H 3010

Spin excitations in CePdAl — •S. Woitschach¹, O. Stockert¹, M. Koza², V. Fritsch³, H. v. Löhneysen³, and F. Steglich¹ — ¹Max-Planck-Institut CPfS, Dresden, Germany — ²Institut Laue-Langevin, Grenoble, France — ³Karlsruher Institut für Technologie, Physikalisches Institut, Karlsruhe, Germany

The heavy-fermion compound CePdAl orders antiferromagnetically below the Néel temperature T_N = 2.7 K. Heat capacity measurements reveal a Kondo temperature of T_K ≈ 5 K. Magnetic order can be continuously suppressed by Ni doping on the Pd site or application of hydrostatic pressure and a quantum critical point is approached. Moreover, as inferred from neutron scattering, geometrical frustration is present in CePdAl. So far, no detailed microscopic measurements have been published on the crystalline electric field (CEF) excitations in CePdAl. Here, we report on our inelastic neutron scattering on CePdAl powder samples to study the characteristic energy scales. The measurements yield the CEF excitations and the quasielastic spin fluctuations. Two excited CEF levels have been detected at ≈ 240 K and >400 K. The results are compared to the thermodynamic measurements.