Differential magnetic susceptibility of the antiferromagnetic crystal , obtained with pulsed magnetization , pulse duration to maximum is . , .
Differential susceptibility surges at the first (a) and second (b) magnetic transitions (leading edge of the field pulse). The complex structure of the surges is evident.
Positions and forms of the surges at the first magnetic transition (field ) for different build-up rates of the magnetic field, . The dark lines show the surges on the leading (a) and trailing (b) edges of a single field pulse. The segment determines the width of the region of fields that corresponds to an equilibrium magnetization process. The time over which the intensity of the external magnetic field changes by the amount at the transition is indicated.
Kink in the field dependence of the differential susceptibility, corresponding to the third magnetic transition.
a—Dependence of the magnetization of in a pulsed magnetic field; the initial temperature of the sample . The magnitude of the moment (left-hand side) is presented per magnetic ion. The error bar shows the maximum error in determining the magnetic moment at saturation. b—Schematic variation of the magnetization as a function of the magnetic field for the model studied in this work; . The dotted line shows the experimental curve. The dashed lines mark the phases with magnetization , , , and (see Fig. 6).
Expected magnetic structures formed in under the influence of a magnetic field : (a), ferrimagnetic phase in the field intervals (b) and (c), respectively, saturated paramagnet (d); —exchange between the nearest neighbors, , —exchange between the more distant neighbors along the and axes. The magnetic field is directed along the axis.
Nonlinear increase of the magnetization of the sample as the second phase transition is approached (trailing edge of the pulse). The curves 1, 2, and 3 were obtained from the expression (5), describing the magnetization process taking account of the thermal fluctuations with values of the parameter , 112, and , respectively. The circles show the magnetization curve obtained experimentally. The adjustable parameters are: and .
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