Spin dynamics and spin freezing at ferromagnetic quantum phase transitions

• Published in: The European physical journal. ST, Special topics Special topics, 2015-07, Vol.224 (6), p.1041-1060
• Main Authors: Schmakat, P., Wagner, M., Ritz, R., Bauer, A., Brando, M., Deppe, M., Duncan, W., Duvinage, C., Franz, C., Geibel, C., Grosche, F.M., Hirschberger, M., Hradil, K., Meven, M., Neubauer, A., Schulz, M., Senyshyn, A., Süllow, S., Pedersen, B., Böni, P., Pfleiderer, C.
• Format: Article
• Language: English
• Subjects: Atomic; Classical and Continuum Physics; Condensed Matter Physics; Materials Science; Measurement Science and Instrumentation; Molecular; Optical and Plasma Physics; Physics; Physics and Astronomy; Quantum Phase Transitions in Correlated Electron Systems; Review
• ISSN: 1951-6355; 1951-6401
• DOI: 10.1140/epjst/e2015-02445-4

We report selected experimental results on the spin dynamics and spin freezing at ferromagnetic quantum phase transitions to illustrate some of the most prominent escape routes by which ferromagnetic quantum criticality is avoided in real materials. In the transition metal Heusler compound Fe 2 TiSn we observe evidence for incipient ferromagnetic quantum criticality. High pressure studies in MnSi reveal empirical evidence for a topological non-Fermi liquid state without quantum criticality. Single crystals of the hexagonal Laves phase compound Nb 1− y Fe 2+ y provide evidence of a ferromagnetic to spin density wave transition as a function of slight compositional changes. Last but not least, neutron depolarisation imaging in CePd 1− x Rh x underscore evidence taken from the bulk properties of the formation of a Kondo cluster glass.