Multiple magnetic ordering phenomena evaluated by heat capacity measurements inEr1−xTbxAl2Laves-phase al

Abstract

Heat capacity measurements in zero and applied magnetic fields have been performed on a series of Er 1−x Tb x Al 2 pseudobinary Laves-phase alloys. Different anomalies that change with Tb concentrations have been observed. These anomalies represent multiple magnetic ordering phenomena, similar to those reported in Er 1−x Pr x and Er 1−x Dy x Al 2 alloys. In common, all alloys contain mixtures of lanthanide metals with opposite signs of the second-order Steven's operators, which were believed to cause competition between the magnetoelastic, crystalline electric field, and quadrupolar effects. This competition gives rise to the observed multiple magnetic ordering transitions in Er 1−x Pr x and Er 1−x Dy x Al 2 alloys. Tb and Er also have opposite signs of second-order Steven's factors, and therefore the observed anomalies in the Er 1−x Tb x Al 2 alloys may also be interpreted in terms of competing quadrupolar, magnetoelastic, and crystalline electric field effects. The magnetocaloric properties of the Er 1−x Tb x Al 2 alloy system have also been evaluated.

Use of Stevens coefficients for the prediction of magnetic transitions in pseudobinaryR1−xRx'AlKhan1, Paudyal2, Mudryk3 et al. 2011Phys. Rev. BSelf Cite161100View full textAdd to dashboardCite

“…11,12 The 4f charge density of Er 3+ is a prolate spheroid, whereas the 4f charge densities of The lattice parameter for pure TmAl 2 (7.7757 Å) was taken from the report of Harris et al 21 As shown in the inset of Fig. 1, the lattice parameters depend linearly on the Tb concentration (x).…”

“…It was proposed that the observed behavior is a result of the competition between the magnetoelastic and quadrupolar effects, which is caused by the modification of the magnetic structure due to Dy and Tb doping. 10,11,12 It was also suggested that the modification of the magnetic structure of the Er 1-x Dy x Al 2 and Er 1-x Tb x Al 2 systems was mainly caused by the 4f charge densities of Er 3+ being different from Dy 3+ and Tb…”

“…The phenomena are represented by the appearance of first order peaks in the zero magnetic field heat capacities of the alloys. 8,10,12 The heat capacity peaks appear only in certain Er rich alloys in the series where the Tb and Dy concentrations center around x = 0.25. We note that the heat capacity peaks in Er 1-x Dy x Al 2 and Er 1-x Tb x Al 2 appear in the samples when the exchange interactions in the solvent (e.g.…”

Magnetism of Ho1−xTbxAl2alloys: Critical dependence

“…2 Recent studies showed that when two lanthanides with 4f electron charge densities of different shape are mixed together in pseudo-binary R 1-x R' x Al 2 compounds (R and R' are lanthanide metals where R has a positive second order Stevens' factor and the same for R' is negative ), interesting magnetic phenomena are observed. 3,4,5,6,7 For certain critical concentrations centered at x = 0.25, sharp peaks, representing first order phase transitions, are observed in the heat capacity, C P , data of the R 1-x R' x Al 2 alloys. The peaks are suppressed upon the application of weak magnetic fields.…”

Magnetic and thermal properties of Er75Dy25single crystals

“…24,25 Multiple magnetic ordering transitions were recently discovered in pseudo-binary R 1-x R' x Al 2 alloys, where R and R' are rare earth metals with second order Steven's factors of opposite sign. 27,28,29,30 Hence, mixing of two lanthanide metals can result in unusual behaviors not only in pseudo-binary lanthanide metals but also in rare earth based intermetallic compounds.…”