# Berlin 2015 – wissenschaftliches Programm

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# TT: Fachverband Tiefe Temperaturen

## TT 71: Correlated Electrons: Poster Session

### TT 71.35: Poster

### Mittwoch, 18. März 2015, 15:00–18:00, Poster B

**Scaling of the magnetic response in YbCo**_{2}**Si**_{2} — •A. Hannaske^{1}, K. Schmalzl^{2}, N. Mufti^{1}, C. Geibel^{1}, and O. Stockert^{1} — ^{1}Max-Planck-Institut CPfS, Dresden, Germany — ^{2}JCNS at ILL, Grenoble, France

YbCo_{2}Si_{2} is a moderate heavy-fermion compound and orders antiferromagnetically below *T*_{N} = 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* || [110] exhibiting a critical field *B*_{c}(*T*_{N} = 0) = 2 T where the transition to the paramagnetic phase takes place. Extensive inelastic neutron scattering experiments have been performed on singe-crystalline YbCo_{2}Si_{2} at *B*_{c} 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 *B*_{c}.