Study of magnetic properties of botallackite Cu2(OH)3Br with a distorted triangular lattice

Hydroxy halides M2(OH)3X (M = transition metal, X = Cl, Br, I) represent a family to investigate novel quantum phenomena arising from the magnetic frustration. For instance, via doing Zn into Cu sites in the parent cinoactacamite Cu2(OH)3Cl, herbertsmithite ZnCu3(OH)6Cl2 hosts a perfect two-dimensional kagome magnetic lattice and exhibits quantum spin liquid state without long range magnetic ordering. In this paper, we report a comprehensive study of botallackite Cu2(OH)3Br, a compound with distorted quasi-two dimensional triangular magnetic lattice, via magnetic susceptibility, heat capacity, neutron diffraction, and inelastic neutron scattering measurements. Density functional theory calculations to understand the exchange interactions of this system will be briefly discussed as well.