Browsing by Author "Tegus, O"

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    Magnetic phase transition in MnFeP0.5As0.4Si 0.1
    (Institute of Physics, 2010-05-13) Wang, JL; Campbell, SJ; Tegus, O; Bruck, E; Dou, SX
    We have carried out a detailed investigation of the magnetic phase transition in MnFeP0.5As0.4Si0.1. Temperature hysteresis has been observed in the variable temperature magnetization curves (Bappl = 0.01 T) with TC W ~ 302 K on warming and TCC ~ 292 K on cooling. The first order nature of this transition in MnFeP0.5As0.4Si0.1 is confirmed by the negative slope obtained from isotherms of M2 versus B/M around the critical temperature. Linear thermal expansion measurements reveal a large volume change, ΔV/V∼8.7×10-3, at the magnetic phase transition and that this magnetovolume effect is suppressed to ΔV/V ∼ 5.5×10-3 in an applied field of Bappl = 1.0 T. Analyses of 57Fe Mössbauer spectra (4.5 - 300 K) using a random distribution model and taking nearest-neighbour environments into account, indicate that the paramagnetic and ferromagnetic phases coexist over a temperature range of ~ 45 K around the Curie temperature. The Debye temperature for MnFeP0.5As0.4Si0.1 has been evaluated as θD = 350 ± 20 K from the temperature dependence of the average isomer shift. ©2010 IOP Publishing Ltd