Single-crystal growth and study of the mixed spin-dimer system Ba3−xSrxCr2

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− 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% of mixing) were grown in a four-mirror-type optical floating-zone furnace. The magnetic properties of 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 , whereas the interdimer exchange interaction J e is smaller by 7%. These results indicate a noticeable change in the magnetic properties by a random substitution effect.

Tuning the orbital-lattice fluctuations in the mixed spin-dimer system Ba3−xSrxCr2O8Gazizulina1, Quintero-Castro2, Wulferding3 et al. 2018Phys. Rev. BSelf Cite1000View full textAdd to dashboardCite

“…Recently, we showed that introducing Ba in the Sr 3 Cr 2 O 8 system does lead neither to magnetic disorder nor to intragap intensities in the dispersion relation [19]. The Jahn-Teller distortion temperature in Ba 3−x Sr x Cr 2 O 8 is gradually suppressed with decreasing x, as shown in Ref.…”

“…6) as well as the ratio of interto intradimer interaction J /J 0 with x. In fact it was found that for Ba 3 Cr 2 O 8 this ratio is slightly larger (J /J 0 = 0.82) than for Sr 3 Cr 2 O 8 (J /J 0 = 0.64) [19]. This subtle difference could be the reason for the fundamentally different dynamics.…”

“…Recently, we reported on the effect of chemical substitution on the magnetic properties of Ba 3−x Sr x Cr 2 O 8 upon partially replacing Sr by Ba by 3.3% and 6.6%. It was found that the intradimer spin-spin interaction is smaller in the mixed compound with x = 2.9 than in pure Sr 3 Cr 2 O 8 by 4%, whereas the interdimer exchange interactions are reduced by 7% [19]. No sign of magnetic disorder was found.…”

“…Single crystals of Ba 3−x Sr x Cr 2 O 8 were grown with x = 2.9 and x = 2.8, as described in Ref. [19]. Heat capacity measurements were performed in a physical property measurement system (PPMS, Quantum Design Inc.).…”

Tuning the orbital-lattice fluctuations in the mixed spin-dimer system Ba$_{3-x}$Sr$_{x}$Cr$_{2}$O$_{8}$

“…Recently, we reported on the effect of chemical substitution on the magnetic properties of Ba 3−x Sr x Cr 2 O 8 upon partially replacing Sr by Ba by 3.3% and 6.6%. It was found that the intradimer spin-spin interaction is smaller in the mixed compound with x = 2.9 than in pure Sr 3 Cr 2 O 8 by 4%, whereas the interdimer exchange interactions are reduced by 7% [17]. No sign of magnetic disorder was found.…”