Phase diagram of the random-field Ising system Fe0.60Zn0.40F2 at intense fields

Magnetic Properties of the Antiferromagnetic Random Energy Model

“…This is accomplished in the present work. It is interesting that recent experimental results in disordered antiferromagnetic systems, like Fe 0X5 Zn 0X5 F 2 [6], exhibiting a possible spin glass phase, show the same qualitative behaviour as found in the present analysis.…”

“…This should be expected for physical reasons since in this case there are less antiferromagnetic bonds which were substituted by ferromagnetic ones thus increasing the number of paralell spins. However, in this model the point T MX points also the onset of a new phase with irreversible behavior as seems to have been observed experimentally in Fe 0X5 Zn 0X5 F 2 [6], whose phase diagram may be interpreted as having a mixed spin glass±antiferromagnetic phase.…”

“…By disordering the system, the low temperature magnetization below T MX (which marks the onset of the mixed spin glass±antiferromagnetic phase) is always bigger than for the pure system. This excessive magnetization is experimentally measurable, see [6] and references therein. This should be expected for physical reasons since in this case there are less antiferromagnetic bonds which were substituted by ferromagnetic ones thus increasing the number of paralell spins.…”

Ordering in the dilute weakly anisotropic antiferromagnetMn0.35Zn0.65F

“…Indeed, for all measured samples of both systems for which the REIM character is found at H = 0, the application of a small field parallel to the easy axis generates critical behavior compatible with the predicted [8] REIM to RFIM crossover scaling. In spite of the evidence supporting the DAFF as a realization of the RFIM, some nonequilibrium features inherent to DAFF compounds and also the newly explored field limits [11][12][13] of the weak RFIM problem in d = 3 make the nature of the phase transition at T c (H) still a matter of considerable controversy [14][15][16].…”

“…Faraday rotation [6] and neutron scattering [21] experiments on a sample with the same x, confirmed the REIM to RFIM crossover scaling at low H and the lack of stability of the AF LRO at large H, giving way to a random-field induced glassy phase in this highly diluted compound. Recent magnetization measurements indicated that similar structure in the phase diagram exists at very high fields for samples with higher values of x [11,12]. At a still higher concentration the low temperature hysteresis observed for x < 0.8 is absent [22].…”