New insight into the thermodynamics of Heisenberg ferromagnets as inferred from high-temperature series

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• 作者：M.D. Kuz'min
• 关键词：Ferromagnetism ; Equation of state ; Landau's theory
• 刊名：Physica B: Condensed Matter
• 出版年：2017
• 出版时间：1 February 2017
• 年：2017
• 卷：506
• 期：Complete
• 页码：48-54
• 全文大小：590 K
• 卷排序：506

文摘

In search of a suitable equation of state for ferromagnets, we revise the information about the Heisenberg model obtainable from high-temperature series. Special attention is paid to the ratio χ3/χ4χ3/χ4 (where χ⁢and⁢χ3 are the linear and cubic susceptibilities) related to Landau's quartic coefficient b  . It is found in particular that both χ3/χ4χ3/χ4 and b   tend to a finite limit as T→TCT→TC. This limit is small — an order of magnitude smaller than predicted by Weiss's molecular field and similar theories — but contrary to the common belief, nonzero. This implies a rejection of the generally accepted critical-point exponents and a return to those of Landau: α=0α=0, β=12, γ=1γ=1, etc.