Berlin 2015 – wissenschaftliches Programm
TT 71.18: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
NMR on the quantum critical ferromagnet YbNi4P2: Evidence for a large basal plane local anisotropy — •Rajib Sarkar1, Marco Günter1, Cornelius Krellner3, Michael Baenitz2, Christoph Geibel2, and Hans-Henning Klauss1 — 1IFP, TU Dresden, D-01069 Dresden, Germany — 2MPI-CPFS, D-01187 Dresden, Germany — 3Goethe University Frankfurt, D-60438 Frankfurt am Main, Germany
In the last 10 years there was growing evidence both from theoretical work and experimental observations that a ferromagnetic (FM) quantum critical point (QCP) cannot exist in a pure system, because the transition becomes first order before reaching the QCP. Therefore the recent report of clear evidence for a FM-QCP in the heavy fermion compound YbNi4P2 attracted considerable attention. While the Bravais lattice of this compound is tetragonal, resulting in isotropic in- plane macroscopic magnetic properties, the local symmetry on the Yb site (and on the P-site) is lower, orthorhombic. Therefore some in- plane anisotropy of local magnetic properties is expected, which could however not yet been studied because of the absence of related effects on macroscopic properties. We performed 31P NMR investigations on a grain aligned polycrystalline sample of YbNi4P2. We observed three structures in the NMR spectra, which present quite different T-dependence of the respective Knight shifts. An analysis of these results provides a clear evidence for strong local in-plane anisotropy of the Yb-moment due to the orthorhombic crystal electric field. Implication for the magnetic ordered state shall be discussed.