Single crystal growth and study of the magnetic properties of the mixed spin-dimer system Ba${}_{3-x}$Sr${}_x$Cr${}_2$O${}_8$

Abstract

The compounds Sr${}_3$Cr${}_2$O${}_8$ and Ba${}_3$Cr${}_2$O${}_8$ are insulating dimerized antiferromagnets with Cr${}^{5+}$ magnetic ions. These spin-$\frac{1}{2}$ ions form hexagonal bilayers with a strong intradimer antiferromagnetic interaction, that leads to a singlet ground state and gapped triplet states. We report on the effect on the magnetic properties of Sr${}_3$Cr${}_2$O${}_8$ by introducing chemical disorder upon replacing Sr by Ba. Two single crystals of Ba${}_{3-x}$Sr${}_x$Cr${}_2$O${}_8$ with $x=2.9$ (3.33\% of $mixing$) and $x=2.8$ (6.66\%) were grown in a four-mirror type optical floating-zone furnace. The magnetic properties on these compounds were studied by magnetization measurements. Inelastic neutron scattering measurements on Ba${}_{0.1}$Sr${}_{2.9}$Cr${}_2$O${}_8$ were performed in order to determine the interaction constants and the spin gap for $x=2.9$. The intradimer interaction constant is found to be $J_0$=5.332(2) meV, about 4\% smaller than that of pure Sr${}_3$Cr${}_2$O${}_8$, while the interdimer exchange interaction $J_e$ is smaller by 6.9\%. These results indicate a noticeable change in the magnetic properties by a random substitution effect.

References in corpus (4)

• Bose-Einstein Condensation in Magnetic Insulators
• Bose-Einstein Condensation of Triplons in Ba3Cr2O8
• Nuclear Magnetic Resonance Reveals Disordered Level-Crossing Physics in the Bose-Glass Regime of the Br-doped Ni(Cl${}_{1-x}$Br${}_x$)${}_2$-4SC(NH${}_2$)${}_2$ Compound at a High Magnetic Field
• Influence of disorder on the structural phase transition and magnetic interactions in Ba${}_{3-x}$Sr${}_x$Cr${}_2$O${}_8$