We study the temperature and magnetic field dependence of the magnetization ( $$ M $$ ) and the inverse susceptibility (χ−1) in the metal–organic frameworks, in particular, for (CH3)2NH2FeIIINiII(HCOO)6 (DMFeNi) and (CH3)2NH2FeIIICuII(HCOO)6 (DMFeCu) close to their magnetic phase transitions. The Landau phenomenological model is employed to analyze the experimental data for the $$ M\left( {T, H} \right) $$ from the literature and to calculate χ−1(T, H) of DMFeNi and DMFeCu. Our results indicate that the thermodynamic model studied explains adequately the observed behavior of $$ M\left( {T, H} \right) $$ for DMFeNi and DMFeCu, which exhibit a weakly first-order (or nearly second order) magnetic phase transition.

中文翻译：

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计算接近 (CH3)2NH2FeIIINiII(HCOO)6 和 (CH3)2NH2FeIIICuII(HCOO)6 中磁相变的磁化率和磁化率

我们研究了金属-有机骨架中磁化强度 ($$M$$) 和逆磁化率 (χ−1) 的温度和磁场依赖性，特别是对于 (CH3)2NH2FeIIINiIII(HCOO)6 (DMFeNi) 和(CH3)2NH2FeIIICuII(HCOO)6 (DMFeCu) 接近它们的磁相变。Landau 现象学模型用于分析文献中 $$ M\left( {T, H} \right) $$ 的实验数据，并计算 DMFeNi 和 DMFeCu 的 χ−1(T, H)。我们的结果表明，所研究的热力学模型充分解释了观察到的 DMFeNi 和 DMFeCu 的 $$ M\left( {T, H} \right) $$ 行为，它们表现出弱的一阶（或接近二阶）磁相过渡。