Berlin 2015 – wissenschaftliches Programm
TT 71.35: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
Scaling of the magnetic response in YbCo2Si2 — •A. Hannaske1, K. Schmalzl2, N. Mufti1, C. Geibel1, and O. Stockert1 — 1Max-Planck-Institut CPfS, Dresden, Germany — 2JCNS at ILL, Grenoble, France
YbCo2Si2 is a moderate heavy-fermion compound and orders antiferromagnetically below TN = 1.7 K. In zero magnetic field two ordered phases occur. The low-temperature commensurate magnetic structure with an ordering wave vector k = (0.25 0.25 1) can be continuously suppressed in a magnetic field B ||  exhibiting a critical field Bc(TN = 0) = 2 T where the transition to the paramagnetic phase takes place. Extensive inelastic neutron scattering experiments have been performed on singe-crystalline YbCo2Si2 at Bc as a function of temperature. The magnetic response of the ordering wave vector shows a critical slowing down when lowering the temperature down to zero indicating the proximity to quantum criticality. Furthermore, the response has been analyzed with respect to possible scaling behavior. Assuming a spin-density-wave scenario with three-dimensional quantum-critical spin fluctuations leads to a better collapse of all measured data points than a scenario with local critical fluctuations. This finding is in line with results of the specific heat, which doesn’t show any sign of divergence at lowest T at the critical field Bc.