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| VOLUME 63 (1996) | ISSUE 8 |
PAGE 594
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External field in Landau theory of the weakly-first-order phase transition. Effect of uniaxial pressure on the orientational ordering in solid C70
Fradkin M.A.
The effect of external conjugated field on the weakly-discontinuous first-order phase transition is analyzed within Landau theory. The third-degree term in the Ginzburg—Landau expansion is shown to preserve the phase transition for some external fields in a contrast with the second-order case. The free energy expansion is shown to correspond to the second-order phase transition under the action of "effective" external field, that depends on both temperature and real field. The case of orientational phase transition in solid C70 is considered and the transition thermoelastic phenomena caused by the coupling of order parameter with elastic strain is analyzed. It is shown that the uniaxial mechanical pressure along the direction of 3-fold axis appears to be an external conjugated field for orientational ordering in crystalline C70. PACS: 05.70.Fh, 64.10.+h, 81.30.Kf
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![](/ps/960/article_14646_800_head.png "<b>The effect of external conjugated field on the weakly-discontinuous first-order phase transition is analyzed within Landau theory. The third-degree term in the Ginzburg—Landau expansion is shown to preserve the phase transition for some external fields in a contrast with the second-order case. The free energy expansion is shown to correspond to the second-order phase transition under the action of "effective" external field, that depends on both temperature and real field. The case of orientational phase transition in solid </b><b>C70 </b><b>is considered and the transition thermoelastic phenomena caused by the coupling of order parameter with elastic strain is analyzed. It is shown that the uniaxial mechanical pressure along the direction of 3-fold axis appears to be an external conjugated field for orientational ordering in crystalline </b><b>C70.</b> <b>PACS: 05.70.Fh, 64.10.+h, 81.30.Kf</b>")