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TT: Fachverband Tiefe Temperaturen

TT 79: Correlated Electrons - Poster Session

TT 79.9: Poster

Mittwoch, 2. April 2014, 15:00–19:00, P2

Effect of Ni-doping on the geometrically frustrated heavy-fermion system CePdAl — •Stefan Lucas¹, Zita Huesges¹, Sarah Woitschach¹, Oliver Stockert¹, Veronika Fritsch², and Hilbert von Löhneysen² — ¹Max Planck Institute CPfS, Dresden, Germany — ²Karlsruhe Institute of Technology, Karlsruhe, Germany

The heavy-fermion compound CePdAl is an interesting system for investigations of quantum criticality in combination with geometric magnetic frustration, which arises from the hexagonal crystal structure of the system. In zero magnetic field, the Néel temperature of 2.7 K can be reduced by doping nickel on the palladium sites. At a doping level of about 14 %, the Néel temperature becomes zero and a quantum critical point is reached. To follow the magnetic order upon nickel doping and investigate the effect of magnetic frustration closer to the quantum critical point, we performed extensive heat capacity measurements on a 5 % Ni-doped single crystal. CePd_0.95Ni_0.05Al orders below T_N ≈ 1.85 K via a second-order phase transition in contrast to the weakly first-order transition in pure CePdAl. Our measurements reveal for CePd_0.95Ni_0.05Al a critical magnetic field B_C ≈ 3 T (B ∥ c, T → 0) to fully suppress the antiferromagnetic phase. We will discuss the resulting magnetic B−T phase diagram and compare it with the parent compound CePdAl.