Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia.
Phys Rev Lett. 2013 May 24;110(21):217211. doi: 10.1103/PhysRevLett.110.217211. Epub 2013 May 23.
We report the dramatic effect of applied pressure and magnetic field on the layered intermetallic compound Pr(0.5)Y(0.5)Mn(2)Ge(2). In the absence of pressure or magnetic field this compound displays interplanar ferromagnetism at room temperature and undergoes an isostructural first order magnetic transition (FOMT) to an antiferromagnetic state below 158 K, followed by another FOMT at 50 K due to the reemergence of ferromagnetism as praseodymium orders (T(C)(Pr)). The application of a magnetic field drives these two transitions towards each other, whereas the application of pressure drives them apart. Pressure also produces a giant magnetocaloric effect such that a threefold increase of the entropy change associated with the lower FOMT (at T(C)(Pr)) is seen under a pressure of 7.5 kbar. First principles calculations, using density functional theory, show that this remarkable magnetic behavior derives from the strong magnetoelastic coupling of the manganese layers in this compound.
我们报告了外加压力和磁场对层状金属间化合物 Pr(0.5)Y(0.5)Mn(2)Ge(2)的显著影响。在没有压力或磁场的情况下，该化合物在室温下表现出面内铁磁性，并在 158 K 以下经历同构一级磁转变（FOMT）到反铁磁态，随后由于镨有序（T(C)(Pr)）重新出现，又发生另一个 FOMT 在 50 K。磁场的施加将这两个转变推向彼此，而压力的施加则将它们分开。压力还产生了巨大的磁热效应，以至于在 7.5 kbar 的压力下，与较低的 FOMT（在 T(C)(Pr)）相关的熵变化增加了三倍。使用密度泛函理论的第一性原理计算表明，这种显著的磁行为源自于该化合物中锰层的强烈磁弹性耦合。
