Transition from vibronic to itinerant electronic behavior

The FM phase is also stabilized by pressure. In an x = 0.15 sample, we [199] found a transition from vibronic to itinerant electronic behavior in the pressure range 5 < P < 6 kbar and the temperature range Tco < T < Tc it marks the FV-FM transition. A neutron-diffraction study [220] of an x = 0.165 sample showed that pressure stabilizes the R-rhombohedral phase relative to the O phase. We have also found that Tc jumps discontinuously by about 15-20 °C not only at the first-order O —O transition, but also at the FV-FM and the 0 -R transitions [199, 220a]. In addition, the slope dTc/dP drops discontinuously on crossing each transition. 

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