In this work, we report the contrasting magnetic behaviour of a bimorphic intermetallic compound TbPt₃ that undergoes a structural phase transformation from cubic AuBe₅-type structure to the cubic AuCu₃-type structure on annealing at high temperature for a very short time. The magnetic ground state configuration of TbPt₃ changes from ferromagnetic (FM) in AuBe₅-type crystalline phase to antiferromagnetic (AFM) in AuCu₃-type phase. However, the AFM ground state of the AuCu₃-type compound is unstable, as a moderate magnetic field can induce the FM character through metamagnetic transformation. To understand the said crystallographic as well as magnetic transformations, structural and magnetic ab-initio calculations have been carried out for both phases. From theoretical calculations we have proposed that although the AuBe₅-type structure of TbPt₃ irreversibly transforms to the AuCu₃-type TbPt₃ by a very short heat treatment, the application of moderate magnetic field on AuCu₃-type structure may result in recovering the magnetic properties of AuBe₅-type structure of TbPt₃. As the two different polymorphs exist simultaneously at ambient condition, TbPt₃ thus provides us a great opportunity to study directly the effect of crystal structure on its physical properties and vice versa.

在这项工作中，我们报告了双晶金属间化合物 TbPt ₃的对比磁行为，该化合物在很短的时间内高温退火时经历了从立方 AuBe ₅型结构到立方 AuCu _{3型结构的结构相变。TbPt 3}的磁性基态构型从AuBe ₅型晶相中的铁磁(FM)转变为AuCu ₃型相中的反铁磁(AFM) 。然而，AuCu _{3的 AFM 基态}型化合物不稳定，因为适度的磁场可以通过超磁转变诱导FM特性。为了理解所述晶体学和磁性转变，已经对两个相进行了结构和磁性从头算计算。从理论计算我们提出虽然TbPt _{3的AuBe 5}型结构通过很短的热处理不可逆地转变为AuCu ₃型TbPt _{3 ，但在AuCu 3}型结构上施加中等磁场可能导致恢复TbPt ₃的AuBe ₅型结构的磁性. 由于两种不同的多晶型在环境条件下同时存在，因此 TbPt ₃为我们提供了一个很好的机会来直接研究晶体结构对其物理性质的影响，反之亦然。