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arXiv · 1512.04571

Dilution effects in spin 7/2 systems. The case of the antiferromagnet GdRhIn$_5$

Raimundo Lora Serrano·Daniel Julio Garcia·Diana Betancourth·Robert Prudêncio Amaral·Nilmar Camilo·Ernesto Estévez Rams·Luis Antonio Ortellado Gómez Zelada·Pascoal Giglio Pagliuso
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Abstract

We report the structural and magnetic characterization of La-substituted Gd$_{1-x}$La$_x$RhIn$_5$ ($x\leq$ 0.50) antiferromagnetic (AFM) compounds. The magnetic responses of pure GdRhIn$_5$ are well described by a $S=7/2$ Heisenberg model. When Gd$^{3+}$ ions are substituted by La$^{3+}$, the maximum of the susceptibility and the inflection point of the magnetic specific heat are systematically shifted to lower temperatures accompanied by a broadening of the transition. The data is qualitatively explained by a phenomenological model which incorporates a distribution of magnetic regions with different transition temperatures ($T_N$). The universal behaviour of the low temperature specific heat is found for La (vacancies) concentrations below $x=0.40$ which is consistent with spin wave excitations. For $x=0.5$ this universal behaviour is lost. The sharp second order transition of GdRhIn$_5$ is destroyed, as seen in the specific heat data, contrary to what is expected for a Heisenberg model. The results are discussed in the context of the magnetic behavior observed for the La-substituted (Ce,Tb,Nd)RhIn$_5$ compounds.

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Raimundo Lora Serrano, Daniel Julio Garcia, Diana Betancourth, Robert Prudêncio Amaral, Nilmar Camilo, Ernesto Estévez Rams, Luis Antonio Ortellado Gómez Zelada, Pascoal Giglio Pagliuso. 2015-12-14. Dilution effects in spin 7/2 systems. The case of the antiferromagnet GdRhIn$_5$. https://doi.org/10.1016/j.jmmm.2015.12.093

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