Low-temperature magnetic properties of the S = 1/2 kagomé antiferromagnet YCo3(OH)6.55Br2.45

We report the synthesis, crystal structure, magnetization and specific heat studies of YCo 3 (OH) 6.55 Br 2.45 single crystal. YCo 3 (OH) 6.55 Br 2.45 crystallizes in trigonal structure, in which Co 2+ ions form a perfect kagomé lattice. The magnetic susceptibility reveals successive magnetic transitions at 6.5 and 7.8 K and the Curie–Weiss fitting demonstrates that YCo 3 (OH) 6.55 Br 2.45 has strong antiferromagnetic coupling and pronounced magnetic frustration effect. Specific heat data suggest that low- T magnetic transitions are attributed to antiferromagnetic ordering of Co 2+ ions and the magnetic entropy points to effective 1/2 spin in the system. These results indicate that an unusual magnetic ordering state with effective spin-1/2 is realized in kagomé lattice system YCo 3 (OH) 6.55 Br 2.45 .