Magnetic ground state and two-dimensional behavior in pseudo-kagome layered system Cu3Bi(SeO3)2O2Br

Abstract

Anisotropic magnetic properties of a layered kagome-like system Cu${}_{3}$Bi(SeO${}_{3}$)${}_{2}$O${}_{2}$Br have been studied by bulk magnetization and magnetic susceptibility measurements as well as powder and single-crystal neutron diffraction. At ${T}_{N}=27.4$ K the system develops an alternating antiferromagnetic order of ($ab$) layers, which individually exhibit canted ferrimagnetic moment arrangement, resulting from the competing ferro- and antiferro-magnetic intralayer exchange interactions. A magnetic field ${B}_{C}\ensuremath{\sim}0.8$ T applied along the $c$ axis (perpendicular to the layers) triggers a metamagnetic transition, when every second layer flips, i.e., resulting in a ferrimagnetic structure. Significantly higher fields are required to rotate the ferromagnetic component towards the $b$ axis ($\ensuremath{\sim}$7 T) or towards the $a$ axis ($\ensuremath{\sim}$15 T). The estimates of the exchange coupling constants and features indicative of an $\mathit{XY}$ character of this quasi-2D system are presented.