Distinct magnetic regimes through site-selective atom substitution in the frustrated quantum antiferromagnet Cs$_2$CuCl$_{4-x}$Br$_x$

P. T. Cong; B. Wolf; M. de Souza; N. Krueger; A. A. Haghighirad; S. Gottlieb- Schoenmeyer; F. Ritter; W. Assmus; I. Opahle; K. Foyevtsova; H. O. Jeschke; R. Valenti; L. Wiehl; M. Lang

doi:10.1103/physrevb.83.064425

arXiv · 1012.2269

Distinct magnetic regimes through site-selective atom substitution in the frustrated quantum antiferromagnet Cs$_2$CuCl$_{4-x}$Br$_x$

P. T. Cong·B. Wolf·M. de Souza·N. Krueger·A. A. Haghighirad·S. Gottlieb- Schoenmeyer·F. Ritter·W. Assmus·I. Opahle·K. Foyevtsova·H. O. Jeschke·R. Valenti·L. Wiehl·M. Lang

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Abstract

We report on a systematic study of the magnetic properties on single crystals of the solid solution Cs$_2$CuCl$_{4-x}$Br$_x$ (0 $\leq$ x $\leq$ 4), which include the two known end-member compounds Cs$_2$CuCl$_4$ and Cs$_2$CuBr$_4$, classified as quasi-two-dimensional quantum antiferromagnets with different degrees of magnetic frustration. By comparative measurements of the magnetic susceptibility $\chi$($T$) on as many as eighteen different Br concentrations, we found that the inplane and out-of-plane magnetic correlations, probed by the position and height of a maximum in the magnetic susceptibility, respectively, do not show a smooth variation with x. Instead three distinct concentration regimes can be identified, which are separated by critical concentrations x$_{c1}$ = 1 and x$_{c2}$ = 2. This unusual magnetic behavior can be explained by considering the structural peculiarities of the materials, especially the distorted Cu-halide tetrahedra, which support a site-selective replacement of Cl- by Br- ions. Consequently, the critical concentrations x$_{c1}$ (x$_{c2}$) mark particularly interesting systems, where one (two) halidesublattice positions are fully occupied.

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P. T. Cong, B. Wolf, M. de Souza, N. Krueger, A. A. Haghighirad, S. Gottlieb- Schoenmeyer, F. Ritter, W. Assmus, I. Opahle, K. Foyevtsova, H. O. Jeschke, R. Valenti, L. Wiehl, M. Lang. 2010-12-10. Distinct magnetic regimes through site-selective atom substitution in the frustrated quantum antiferromagnet Cs$_2$CuCl$_{4-x}$Br$_x$. https://doi.org/10.1103/physrevb.83.064425

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