Structural characterization and magnetic properties of chromium jarosite KCr3(OD)6(SO4)2

Sofie Janas, Mathilde B Sørensen, Anders B A Andersen, Mikkel Juelsholt, Martin Boehm, Kasper Steen Pedersen, Kirsten M Ø Jensen, Kim Lefmann, Ulla Gro Nielsen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Potassium chromium jarosite, KCr3(OH)6(SO4)2 (Cr-jarosite), is considered a promising candidate to display spin liquid behavior due to the strong magnetic frustration imposed by the crystal structure. However, the ground state magnetic properties have been debated, since Cr-jarosite is notoriously non-stoichiometric. Our study reports the magnetic properties for deuterated KCr3(OD)6(SO4)2 on chemically well-defined samples, which have been characteried by a combination of powder X-ray diffraction, neutron diffraction, solid state NMR spectroscopy, and scanning electron microscopy with energy dispersive spectroscopy. Eight polycrystalline samples, which all contained only 1-3% Cr vacancies were obtained. However, significant substitution (2-27%) of potassium with H2O and/or H3O+ was observed and resulted in pronounced stacking disorder along the c-axis. A clear second-order transition to an antiferromagnetically ordered phase at TN = 3.8(1) K with a small net moment of 0.03 μB per Cr3+-ion was obtained from vibrating sample magnetometry and temperature dependent neutron diffraction. The moment is attributed to spin canting caused by the Dzyaloshinskii-Moriya interaction. Thus, our experimental results imply that even ideal potassium chromium jarosite will exhibit magnetic order below 4 K and therefore it does not qualify as a true spin liquid material.

Original languageEnglish
JournalPhysical Chemistry Chemical Physics
ISSN1463-9076
DOIs
Publication statusAccepted/In press - 2020

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