paper

Distinct magnetic regimes through site-selective atom substitution in the frustrated quantum antiferromagnet Cs $_{2}$ CuCl $_{4 - x}$ Br $_{x}$

arXiv:1012.2269 · doi:10.1103/PhysRevB.83.064425

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 $I ¨ $ ( $T$ ) 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 $_{c 1}$ = 1 and x $_{c 2}$ = 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 $_{c 1}$ (x $_{c 2}$ ) mark particularly interesting systems, where one (two) halidesublattice positions are fully occupied.

15 pages, 4 figures

Distinct magnetic regimes through site-selective atom substitution in the frustrated quantum antiferromagnet Cs2​CuCl4−x​Brx​

Abstract

Distinct magnetic regimes through site-selective atom substitution in the frustrated quantum antiferromagnet Cs $_{2}$ CuCl $_{4 - x}$ Br $_{x}$