Magnetic X-ray scattering study of random field effects in Mn0.75Zn0.25F2

Monte Carlo Studies of Ising Spin Glasses and Random Field Systems

“…This hints at a first order phase transition, a possibility that has already been suggested by Young and Nauenberg [301] (see however the interpretation of X-ray scattering studies by Hill et al [122]). Note that β = 0 is also found for a continuous distribution [233], which is important since in case of a binary distribution for larger field strength a tricritical point is predicted in mean field theory [1], which separates a first order (high fields) from a second order (low fields) transition line in the h − T -diagram.…”

The Non-Resonant Magnetic X-ray Scattering Cross Section of MnF2. 2. High-Energy X-ray Diffraction at 80keV

“…Of course, this argument is also valid for medium X-ray energies around 10keV. However, these probe only a near-surface region where the critical behavior can easily be influenced by surface defects (Hill, Feng, Birgeneau & Thurston, 1993). Moreover, the intensities obtained for non-resonant X-ray diffraction are much smaller in this energy range (Goldmann et al, 1987).…”

“…This is especially important for the study of magnetically disordered materials. As was shown for the random field magnet Mn0.75Zn0.25F 2 (Hill, Feng, Birgeneau & Thurston, 1993), surface preparation affects drastically the magnetic properties in a near-surface region since domains are pinned to surface defects, like scratches. While this is a rather interesting phenomenon, the intrinsic disorder effects can safely be studied only with a true bulk probe.…”

Neutron and x-ray scattering studies of field-cooled orderingin the three-dimensional random-field Ising model

“…As discussed in the preceding paper, it has proven to be an ideal tool for measuring the order parameter in the ZFC transition, 12,26,23 and has also led to unexpected discoveries on field cooling. In a magnetic x-ray scattering study on a sample of Mn 0.75 Zn 0.25 F 2 , Hill et al observed long range ordering in the field-cooled state, 29,12 in apparent contradiction with neutron scattering results for which field-cooled long range order was not observed. To date, however, this remains the only evidence of long range magnetic order in a field-cooled DAFF and it is therefore important to investigate further this unexpected phenomenon.…”

“…When cooled in a field, the sample falls out of equilibrium, at T M (H), and develops a metastable short range ordered ͑SRO͒ domain state without ever achieving long range order. This type of hysteresis has been observed directly by neutron and magnetic x-ray scattering [5][6][7][8][9][10][11][12] and indirectly by many techniques including uniform magnetization, 13,14 Faraday rotation, 15 linear magnetic birefringence, 16 and thermal expansion. 17 The disparate behavior of the ZFC and the FC protocols has also been observed in Monte Carlo simulations.…”