Instability of long-range order in a d = 3 random-field Ising model system: Fe xZn1-xF2

Instabilities of long-range order are observed in samples of the d = 3 dilute uniaxial antiferromagnet Fe xZn1-xF2 with x = 0:56 and 0.41, under strong random fields. The onset of instability, mapped in the (H, T) phase diagrams of the samples, reveals that the H, T and x dependence of the effective random field is in qualitative agreement with a mean-field expression predicted in the weak-field limit for site diluted antiferromagnets.

Authorship

F. C. Montenegro

Universidade Federal de Pernambuco, Departamento de Física , Recife, , BrazilUniversidade Federal de PernambucoBrazilRecife, , BrazilUniversidade Federal de Pernambuco, Departamento de Física , Recife, , Brazil

K. A. Lima

M. S. Torikachvili

San Diego State University, Department of Physics , San Diego, CA, USASan Diego State UniversityUSASan Diego, CA, USASan Diego State University, Department of Physics , San Diego, CA, USA

A. H. Lacerda

Los Alamos National Laboratory, National High Magnetic Field Laboratory , Pulse Facility, Los Alamos, NM, USALos Alamos National LaboratoryUSALos Alamos, NM, USALos Alamos National Laboratory, National High Magnetic Field Laboratory , Pulse Facility, Los Alamos, NM, USA

SCIMAGO INSTITUTIONS RANKINGS

San Diego State University, Department of Physics , San Diego, CA, USASan Diego State UniversityUSASan Diego, CA, USASan Diego State University, Department of Physics , San Diego, CA, USA

Figures

Figures (7)

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Figure 1. Time dependence of the magnetization M(t) following the FI procedure (see text) at T = 10 K up to H = 10 T, 14 T, 16 T and 17 T. The measurement begins as soon as the field reaches the above values. The magnetization is normalized by the initial value M0, which is plotted versus H in the inset.

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Figure 2. The same as in Fig. 1, but for T = 4 K and H = 10 T, 15 T and 18 T.

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Figure 3.
Critical and irreversibility phase boundaries in Fe_0.56Zn_0.40F₂. Full symbols, with horizontal (or vertical) error bars, represent T_c(H) originating in the position of the peaks in the M vs H (or M vs T) plots (see Ref. 9) for zero-field-cooled Fe_0.56Zn_0.44F₂. The asterisks represent the positions where time dependence of the magnetization were presented in Figs. 1 and 2.

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Figure 4.
Time dependence of the magnetization M(t) following the FI procedure in T = 10.0 K up to H = 2.5 T, 5.0 T and 7.5 T and by field decreasing (FD) the field from the paramagnetic phase to H = 5.0 T and 2.5 T. The magnetization is normalized by the initial value M₀, which is plotted versus H in the inset.

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Figure 5.
The same as in Fig. 4 but for T = 4.0 K and several values of H, both FI and FD procedures.

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Figure 6.
The initial magnetization M₀ plotted versus H for T = 4.0 K in the FI and FD procedures.

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Figure 7.
Critical (full symbols) and irreversibility (open symbols) phase boundaries in Fe_0.41Zn_0.59F₂. The asterisks represent the positions where time dependence of the magnetization are presented in Figs. 4 and 5.

Figure 3. Critical and irreversibility phase boundaries in Fe_0.56Zn_0.40F₂. Full symbols, with horizontal (or vertical) error bars, represent T_c(H) originating in the position of the peaks in the M vs H (or M vs T) plots (see Ref. 9) for zero-field-cooled Fe_0.56Zn_0.44F₂. The asterisks represent the positions where time dependence of the magnetization were presented in Figs. 1 and 2.

Figure 4. Time dependence of the magnetization M(t) following the FI procedure in T = 10.0 K up to H = 2.5 T, 5.0 T and 7.5 T and by field decreasing (FD) the field from the paramagnetic phase to H = 5.0 T and 2.5 T. The magnetization is normalized by the initial value M₀, which is plotted versus H in the inset.

Figure 5. The same as in Fig. 4 but for T = 4.0 K and several values of H, both FI and FD procedures.

Figure 6. The initial magnetization M₀ plotted versus H for T = 4.0 K in the FI and FD procedures.

Figure 7. Critical (full symbols) and irreversibility (open symbols) phase boundaries in Fe_0.41Zn_0.59F₂. The asterisks represent the positions where time dependence of the magnetization are presented in Figs. 4 and 5.

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Instability of long-range order in a d = 3 random-field Ising model system: Fe xZn1-xF2

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