One of the key questions concerning frustrated lattices that has lately emerged is the role of disorder in inducing spin-liquid-like properties. In this context, the quantum kagome antiferromagnets YCu3(OH)6Cl3, which has been recently reported as the first geometrically perfect realization of the kagome lattice with negligible magnetic/non-magnetic intersite mixing and a possible quantum-spin-liquid ground state, is of particular interest. However, contrary to previous conjectures, here we show clear evidence of bulk magnetic ordering in this compound below TN=15\,K by combining bulk magnetization and heat capacity measurements, and local-probe muon spin relaxation measurements. The magnetic ordering in this material is rather unconventional in several respects. Firstly, a crossover regime where the ordered state coexists with the paramagnetic state extends down to TN/3 and, secondly, the fluctuation crossover is shifted far below TN. Moreover, a reduced magnetic-entropy release at TN and persistent spin dynamics that is observed at temperatures as low as T/TN=1/300 could be a sign of emergent excitations of correlated spin-loops or, alternatively, a sign of fragmentation of each magnetic moment into an ordered and a fluctuating part.
@article{arxiv.1904.02878,
title = {Coexistence of magnetic order and persistent spin dynamics in a quantum kagome antiferromagnet with no intersite mixing},
author = {A. Zorko and M. Pregelj and M. Klanjšek and M. Gomilšek and Z. Jagličić and J. S. Lord and J. A. T. Verezhak and T. Shang and W. Sun and J. -X. Mi},
journal= {arXiv preprint arXiv:1904.02878},
year = {2019}
}