Magnetic Structures of Pr0.8Lu0.2Mn2Ge2 and Pr0.6Lu0.4Mn2Ge2



Publication Details

Wang, J. L., Studer, A. J., Campbell, S. J., Kennedy, S. J., Zeng, R., Dou, S. X. Wu, G. H. (2011). Magnetic Structures of Pr0.8Lu0.2Mn2Ge2 and Pr0.6Lu0.4Mn2Ge2. IEEE Transactions on Magnetics, 47 (10), 2893-2896.


The magnetic structures of Pr0.8Lu0.2Mn2Ge2 and Pr0.6Lu0.4Mn2Ge2 have been determined by neutron powder diffraction over the temperature range 10-450 K. On cooling from the paramagnetic region the Mn sublattice of Pr0.8Lu0.2Mn2Ge2 orders in a similar manner to PrMn2Ge2 with first ab-plane intralayer antiferromagnetism (AFl) below TNintra ~ 397 K followed by canted ferromagnetism (Fmc) at TCinter ~ 330 K and then a conical (Fmi) spin structure below Tc/c ~ 192 K. The transition at TCPr=35 K with related enhancement in magnetization, is assigned to the additional ferromagnetic contribution of the Pr sublattice leading to the combined (Fmc+F(Pr)). For Pr0.6Lu0.4Mn2Ge2 the transition from PM to AFl occurs at TNintra ~ 375 K while the canted ferromagnetic (Fmc) state forms at TCinter ~ 321 K . The increased Lu concentration of Pr0.6Lu0.4Mn2Ge2 destroys the incommensurate Fmi conical spin structure of Pr0.8Lu0.2Mn2Ge2. Rather, in common with similar mixed RT2X2 systems (e.g., La1-xYxMn2Si2, La1-xPrxMn2Si2), the Pr0.6Lu0.4Mn2Ge2 compound exhibits co-existence of the AFmc and Fmc phases on cooling from the pure Fmc state. Transformation to the combined ferromagnetic state (Fmc+F(Pr)) takes place on c-axis ordering of the Pr sublattice at TCPr ~ 31 K . In the region of phase co-existence, the Fmc unit cell is larger than the AFmc unit cell indicating strong magneto-structural coupling with a change of the lattice inducing a change of the magnetic state.

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