Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 50: Quantum-Critical Phenomena I
TT 50.4: Vortrag
Mittwoch, 14. März 2018, 10:15–10:30, H 3005
Antiferromagnetic correlations in ferromagnetic YbNi4P2 — •Zita Huesges1, Stefan Lucas2, Kristin Kliemt3, Cornelius Krellner3, Astrid Schneidewind4, and Oliver Stockert2 — 1Helmholtz-Zentrum Berlin GmbH — 2MPI Chemische Physik fester Stoffe, Dresden — 3Goethe-Universität Frankfurt am Main — 4Forschungszentrum Jülich GmbH, Outstation MLZ
YbNi4P2 is one of the very few heavy-fermion compounds that shows ferromagnetic order at very low temperature. The Curie temperature, only 150 mK in the pure compound, can be suppressed to zero by As substitution on the P site. Upon substitution, the transition stays second order, thus leading to a ferromagnetic quantum critical point. While the c-axis is the magnetic easy axis in the paramagnetic phase, magnetic order occurs with the moments aligned in the ab-plane.
To gain microscopic insights into this unusual behaviour, we have performed inelastic neutron scattering (INS) experiments at the triple-axis spectrometers PANDA (MLZ) and FLEXX (HZB). Large single crystals have recently become available due to progress in sample preparation. Remarkably, we observe an INS signal at low-Q antiferromagnetic positions. The signal appears to be quasi-elastic, it is present at much higher temperatures than TC, and it shows no signature of a moment-reorientation. This indicates that only a fraction of the magnetic moment participates in the low-temperature ferromagnetic order, while antiferromagnetic correlations are present in a broader temperature range.