Properties of phase transitions in easy-axis tetragonal antiferromagnets |
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Authors: | G K Chepurnykh V S Ivanii O G Medvedovskaya O A Nikitina |
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Institution: | (1) Institute of Applied Physics, Ukrainian Academy of Sciences, 244030 Sumy, Ukraine |
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Abstract: | Properties of phase transitions in a magnetic field H parallel to the easy axis have been investigated, and it has been shown, in particular, that the nature of the transition
of the magnetic subsystem from the antiferromagnetic phase to the angular phase depends on the “sign” of the Dzyaloshinskii
interaction. The conditions for orientation of the antiferromagnetism vector l in the basis plane in fields larger than the threshold field have been determined. It is shown that the transition from the
angular phase to the state where the resulting magnetic moment m is parallel to the easy axis takes place in the field corresponding to a spin-flip transition. From an analysis of the configuration
of the magnetic subsystem for arbitrary orientation of the external magnetic field, it follows that the values of the critical
angle (ψ
cr
) for which a first-order phase transition takes place satisfy the condition
in the case in which the anisotropy constant f in the basis plane is of the order of the first anisotropy constant b. Usually
so that the tricritical point in the phase diagram H
y
,H
z
satisfies the condition H
y
∼H
z
.
Fiz. Tverd. Tela (St. Petersburg) 41, 2044–2046 (November 1999) |
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Keywords: | |
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