Perfect kagome-lattice antiferromagnets with J$_{eff}$ = 1/2: The Co$^{2+}$-analogs of copper minerals volborthite and vesignieite

TL;DR

This study synthesizes and characterizes Co$^{2+}$ kagome magnets as analogs to copper-based quantum kagome materials, revealing magnetic ground states and field-induced transitions consistent with J$_{eff}$ = 1/2 physics, advancing understanding of kagome magnetism.

Contribution

First experimental realization of Co$^{2+}$ kagome magnets as J$_{eff}$ = 1/2 analogs, exploring their magnetic ground states and field-induced transitions.

Findings

Ground state is A-type antiferromagnetic order.

Low-temperature magnetic field induces a metamagnetic transition.

Magnetic states include canted ferromagnetic components influenced by Dzyaloshinskii-Moriya interactions.

Abstract

We report the synthesis, crystal structure, and magnetic properties of Co$^{2+}$ kagome magnets Co$_3$V$_2$O$_7$(OH)$_2$$\cdot$2H$_2$O and BaCo$_3$(VO$_4$)$_2$(OH)$_2$, which can be recognized as Co-analogues of the intensively researched quantum kagome magnet volborthite Cu$_3$V$_2$O$_7$(OH)$_2$$\cdot$2H$_2$O and vesignieite BaCu$_3$(VO$_4$)$_2$(OH)$_2$. For each compound, the ground state is seemingly A-type antiferromagnetic order. At low temperatures, applying a magnetic field causes a metamagnetic-like transition described by the transition in which antiferromagnetically-aligned canted moments change to ferromagnetically-aligned ones. These ground and field-induced states include a canted ferromagnetic component perpendicular to the kagome planes favored by Dzyaloshinskii-Moriya interactions. These magnetic properties are well characterized by the J$_{eff}$ = 1/2 physics. Our findings will be the first step toward clarifying the J$_{eff}$ = 1/2 kagome physics, which has been little studied experimentally or theoretically.