Magnetic interactions and the pressure phase-diagram of CuGeO3
  A pressure and temperature dependent Raman study of the vibrational and spin dynamics in CuGeO3 is presented. A new low temperature, high pressure phase has been identified, and a pressure-temperature phase-diagram is proposed for CuGeO3. The pressure dependence of the effective exchange interaction, of the spin-Peierls gap, and of the spin-Peierls temperature strongly supports a model in which next nearest neighbor interactions stabilise the SP ground state. The Raman data allow for a quantitative estimate of the pressure dependence of the next nearest neighbor interactions. 
P.H.M. van Loosdrecht (1,2), J. Zeman (1), G. Martinez(1), G. Dhalenne   (3), A. Revcolevschi (3). ((1) Grenoble High Magnet...