Incommensurate spin density wave

Figure 30 Phase diagram of (TMTCFljX proposed by Jerome [95]. PI, SP, C-AF, IC-SDW and SC represent paramagnetic insulating, spin-Peierls, commensurate antiferromagnetic, incommensurate spin density wave and superconducting phases, respectively. Tp denotes the temperature where the resistivity shows the minimum.

ISDW incommensurate spin density wave itinerant magnetism)... 

SC — superconducting, AFM — commensurate antifenomagnet structure, SDW — incommensurate antiferro-magnet order (spin density wave), WFM — weak ferromagnetism Tn — magnetic ordering temperature, Tc — superconducting transition temperature and N(Ep) —density of states at the Fermi level. 

Fig. 26. Different types of magnetic structures in the ground stale of ftNijI C compounds, (a) For R = Pr, Dy or Ho commensurate antiferromagnelic structure, (b, c and d) for R = Er, Tb and Tm incommensurate antiferromagnetic structures (spin density waves) with a propagation vector q in the (a, 6)-plane, (b) Moments in the (a, b) plane and X to q. (c) Moments in the (a, b) plane and q. (d) Moments c and X to q (after Lynn et al.

The previous treatment deals with a one-component order parameter (such as for a commensurate Peierls distortion) but does not apply to situations where the order parameter is complex with an amplitude and a phase (superconductivity, incommensurate Peierls, or spin density wave transitions). The latter situation is analogous to classical moments which can rotate freely in an XY plane. The coherence length of the XY model is less strongly divergent at low temperature than for the Ising model,... 

---