Possibility of field-induced incommensurate order in   quasi-one-dimensional frustrated spin system
  We study an incommensurate long-range order induced by an external magnetic field in a quasi-one-dimensional bond-alternating spin system, F5PNN, focusing on the role of the frustrating interaction which can be enhanced by a high-pressure effect. On the basis of the density matrix renormalization group analysis of a microscopic model for F5PNN, we present several H-T phase diagrams for typical parameters of the frustrating next-nearest-neighbour coupling and the interchain interaction, and then discuss how the field-induced incommensurate order develops by the frustration effect in such phase diagrams. A magnetization plateau at half the saturation moment is also mentioned. 
Nobuya Maeshima, Kouichi Okunishi, Kiyomi Okamoto, T\^oru Sakai, Kenji   Yonemitsu