Perfect kagome-lattice antiferromagnets with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>J</mml:mi><mml:mi>eff</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mstyle scriptlevel="0" displaystyle="false"><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac></mml:mstyle></mml:mrow></mml:math>: The <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:mi>Co</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> analogs of the copper minerals volborthite and vesignieite
Yuya Haraguchi, Takehiro Ohnoda, Akira Matsuo, Koichi Kindo, Hiroko Aruga Katori
Abstract
We report the synthesis, crystal structure, and magnetic properties of ${\mathrm{Co}}^{2+}$ kagome magnets ${\mathrm{Co}}_{3}{\mathrm{V}}_{2}{\mathrm{O}}_{7}{(\mathrm{OH})}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}2{\mathrm{H}}_{2}\mathrm{O}$ and ${\mathrm{BaCo}}_{3}$(${\mathrm{VO}}_{4}{)}_{2}{(\mathrm{OH})}_{2}$, which can be recognized as Co analogs of the intensively researched quantum kagome magnet volborthite ${\mathrm{Cu}}_{3}{\mathrm{V}}_{2}{\mathrm{O}}_{7}{(\mathrm{OH})}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}2{\mathrm{H}}_{2}\mathrm{O}$ and vesignieite ${\mathrm{BaCu}}_{3}$(${\mathrm{VO}}_{4}{)}_{2}{(\mathrm{OH})}_{2}$. For each compound, the ground state is seemingly $A$-type antiferromagnetic order. At low temperatures, applying a magnetic field causes a metamagneticlike transition described by the transition in which antiferromagnetically aligned canted moments change to ferromagnetically aligned ones. These ground and field-induced states include a canted ferromagnetic component perpendicular to the kagome planes favored by Dzyaloshinskii-Moriya interactions. These magnetic properties are well characterized by the ${J}_{\mathrm{eff}}=\frac{1}{2}$ physics. Our findings will be a step toward clarifying the ${J}_{\mathrm{eff}}=\frac{1}{2}$ kagome physics, which has not been thoroughly studied experimentally or theoretically.