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TT: Fachverband Tiefe Temperaturen

TT 56: Correlated Electrons: Quantum-Critical Phenomena

TT 56.4: Vortrag

Donnerstag, 19. März 2020, 10:15–10:30, HSZ 304

Ferromagnetic magnons in YbNi₄P₂ — •Oliver Stockert¹, Kristin Kliemt², Zita Huesges³, Stefan Lucas¹, Cornelius Krellner², Astrid Schneidewind⁴, and Karin Schmalzl⁵ — ¹Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden — ²Physikalisches Institut, Goethe-Universität, Frankfurt am Main — ³Helmholtz-Zentrum für Materialien und Energie, Berlin — ⁴Forschungszentrum Jülich, Outstation MLZ, Garching — ⁵Forschungszentrum Jülich, Outstation ILL, Grenoble

The heavy-fermion compound YbNi₄P₂ exhibits ferromagnetic order below the very low Curie temperature T_C = 150 mK. Upon substituting As for P the ordering temperature T_C in YbNi₄(P_1−xAs_x)₂ can be continuously suppressed with the occurrence of a quantum critical point [1]. So far bulk measurements have been used to characterize the ferromagnetic order in YbNi₄P₂ [2]. In contrast, neutron diffraction failed in detecting any ferromagnetic signal. In order to better characterize the magnetism in YbNi₄P₂, we performed inelastic neutron scattering on a large YbNi₄P₂ single crystal [3] at the triple-axis spectrometers IN12 (ILL, Grenoble), PANDA (MLZ, Garching) and FLEXX (HZB, Berlin). We observe clear magnetic excitations in YbNi₄P₂ at low temperatures with a dispersion as expected for a ferromagnet. Our findings are a direct evidence of the ferromagnetic order in YbNi₄P₂.

[1] A. Steppke et al., Science 339 (2013) 933

[2] C. Krellner, C. Geibel, J. Phys. Conf. Ser. 391 (2012) 012032

[3] K. Kliemt, C.Krellner, J. Crystal Growth 449 (2016) 129.