λ-type molecular π–d systems are coupled systems consisting of π electron systems with strong magnetic interactions and 3d electron systems with weak magnetic interactions. They exhibit an unconventional antiferromagnetic ground state in which the 3d spins behave as if they remain paramagnetic even below T_N. In this study, we investigated the anion substitution effects of λ-(BEDT-STF)₂Fe_xGa_1−xCl₄ by heat capacity measurements. A Schottky-type anomaly was observed for all alloy compounds (0.1 ≤ x ≤ 1.0). We found that the exchange field, which is the origin of this Schottky-type anomaly, decreases with the Fe content. Based on these results, we discuss the role of each magnetic interaction involved in the stabilization of the antiferromagnetic ground state and emergence of paramagnetic-like behavior.

中文翻译：

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阴离子取代对分子π-d系统λ-（BEDT-STF）2FexGa1-xCl4的反常规反铁磁基态的影响

λ型分子π - d系统是由具有强磁性相互作用的π电子系统和具有弱磁性相互作用的3 d电子系统组成的耦合系统。它们表现出非常规的反铁磁性基态，其中3 d自旋的行为就好像它们在T _N以下也保持顺磁性。在这项研究中，我们通过热容测量研究了λ-（BEDT-STF）₂ Fe _x Ga _{1- x} Cl ₄的阴离子取代作用。异常观察到所有合金化合物（0.1 A肖特基型≤ X≤1.0）。我们发现，作为这种肖特基型异常的起源的交换场随Fe含量的增加而减小。基于这些结果，我们讨论了在反铁磁性基态的稳定和顺磁性类似行为的出现中涉及的每个磁性相互作用的作用。