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TT: Fachverband Tiefe Temperaturen

TT 26: CE: Heavy Fermions

TT 26.2: Vortrag

Mittwoch, 24. März 2010, 14:15–14:30, H21

Complex interplay of Ce 4f and Fe 3d magnetism in CeFe(As,P)O as seen from ³¹P and ⁷⁵As NMR. — •Rajib Sarkar, Michael Baenitz, Anton Jesche, Frank Steglich, and Cristoph Geibel — Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

The rare earth (R) transition metal (T) pnictides RTPnO( Pn:P or As) earn special attention because of the high T_C superconductivity in CeFeAsO_1−xF_x, whereas the magnetism of the undoped system stays unexplored. CeFePO is a heavy fermion metal with a high γ value (700 mJ/mol K²) in the vicinity of a ferromagnetic (FM) instability [1]. Here magnetism is solely governed by Ce-4f state whereas in CeFeAsO Fe 3d states themself order AFM at about T≅150 K. Therefore investigation on CeFe(As,P)O allows to study the crossover between Kondo and RKKY physics to 3d magnetic order. Yongkang Luo et. al. recently published a rather complex phase diagram with two critical points obtained from bulk properties. NMR provides a microscopic tool for studying the interplay between Ce 4f and Fe 3d magnetism. We report on ³¹P (I=1/2) and ⁷⁵As (I=3/2) NMR studies on CeFeAs_1−xP_xO with x=0, 0.05, 0.3, and 0.9.

[1] Brüning et . al., PRL 101, 117206 (2008).

[2] Luo et . al., arXiv:0907.2961v1.