Magnetic properties of compounds

Abstract

The structure and magnetic properties of the compounds (x = 0 - 1.0) have been investigated. All the compounds crystallize in -type structure. Substitution of Y for Pr led to a monotonic decrease in the lattice constants and the unit-cell volume. Samples in this alloy system exhibit a crossover from ferromagnetic ordering for to antiferromagnetic ordering for as a function of concentration. The low-temperature behaviours of samples in the range were studied using magnetic measurements. Based on the magnetic measurements the tentative magnetic phase diagram showing three concentration regions of qualitatively different magnetic behaviour has been determined. Increasing substitution of Y for Pr in shows a depression of ferromagnetic ordering and the gradual development of antiferromagnetic ordering. For compounds with the magnetization first shows a clear ferromagnetic transition at , followed by a gradual drop at lower temperature, and then increases again. For compounds with x < 0.4 or , only ferromagnetic ordering or antiferromagnetic ordering occurs respectively.

Driving Magnetostructural Transitions in Layered Intermetallic Compounds

“…On cooling from the paramagnetic region, the first transition from the paramagnetic state (PM) to the intralayer antiferromagnetic (AFl) state occurs at T intra N $ 375 K with the second transition from the AFl magnetic structure to a canted ferromagnetic spin structure (Fmc) occurring at T Given that the magnetic structure in RMn 2 Ge 2 and related systems depends sensitively on composition and the intraplanar Mn-Mn spacing [3][4][5][6]16], the difference in the transition temperatures between those reported earlier [13] and the present study can be understood in terms of the possible compositional variations. Similarly, the magnetization closely approaches zero in the antiferromagnetic region between T inter N and T…”

“…[11]], less insight has been gained on the relationship between magnetovolume effects and the magnetic entropy at magnetic transitions. Pr 0:5 Y 0:5 Mn 2 Ge 2 was selected for this study following our investigation of the Pr 1Àx Y x Mn 2 Ge 2 system [12] in which both the loss of moment in the Pr sublattice and the significant modifications of the magnetic states of the Mn lattice were investigated [13] because it exhibits reentrant ferromagnetism. Our investigation of the structural changes occurring in the reentrant ferromagnet Pr 0:5 Y 0:5 Mn 2 Ge 2 using neutron diffraction in applied magnetic fields, combined with magnetic measurements under hydrostatic pressure has enabled us to develop a new insight into the magnetic behavior of this system and the role of magnetostructural coupling in the magnetocaloric effect.…”

Magnetic transitions and the magnetocaloric effect in the Pr1−xYxMn2Ge2 system

“…(a) Room temperature XRD patterns and Rietveld refinements of the Pr 1− x Y x Mn 2 Ge 2 compounds (Cu Kα radiation); (b) composition dependence of lattice parameters (open symbols taken from Ref. ). The full lines represent linear fits to the present data; the dashed lines indicate the values a crit1 = 4.06 Å and a crit2 = 4.02 Å as discussed in the text.…”

Magnetic phase transitions in Nd1−xYxMn2Ge2 (0 ≤ x ≤ 0.6)

“…In the IM phase bounded by T IM , the canted ferromagnetism progress towards antiferromagnetism as the lattice contracts on decreasing temperature. This is a continuous transition that occurs in a composition range where the critical lattice spacing appears within the temperature range investigated, as found in the Pr 1−x Y x Mn 2 Ge 2 [16], Pr 1−x Dy x Mn 2 Ge 2 [17] and Ce 1−x Dy x Mn 2 Ge 2 [17]. Owing to inhomogeneity of the polycrystal samples, it is difficult to determine the values of T IM and T N1 (Mn) accurately.…”