Possibility of Semicommensurate Phases When the Corresponding Purely Incommensurate Phases Are Forbidden
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The order parameters are assumed to number two, and denoted by Q and Q'. Thefree energy function is denoted by I. Let the degree of anisotropy of I in its gradi-ent-less part be 2a, where (Y is an integer g2. The I,ifshitz term, i.e., Q'8.Q - Q8.Q'and a term expressed as a product of Q' A- Q" or Q' - Q" with Q'8.Q - Q8.Q' are in-terrelated as follows: If one of them is allowed (or forbidden) to exist in cD, the otheris always forbidden (or often allowed). Even if the former term is forbidden and nopurely incommensurate phase is possible, a semicommensurate phase is possible ow-ing to the latter term. (The coefficient to term 8.Q8.Q' is assurned to be positive.) Oncooling, the prototypic phase can transform to the semicommensurate phase earlierthan to the corresponding purely commensurate ferroic phase. A detailed explanationis given.
- 社団法人日本物理学会の論文
- 1989-08-15
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