Spin Liquid Ground State in the Frustrated Kagome Antiferromagnet   MgCu3(OH)6Cl2
  We report muSR experiments on Mg{x}Cu{4-x}(OH)6Cl2 with x \sim 1, a new material isostructural to Herbertsmithite exhibiting regular kagome planes of spin 1/2 (Cu^{2+}), and therefore a candidate for a spin liquid ground state. We evidence the absence of any magnetic ordering down to 20 mK (\sim J/10^4). We investigate in detail the spin dynamics on well characterized samples in zero and applied longitudinal fields and propose a low T defect based interpretation to explain the unconventional dynamics observed in the quantum spin liquid phase. 
E. Kermarrec, P. Mendels, F. Bert, R.H. Colman, A.S. Wills, P.   Strobel, P. Bonville, A. Hillier and A. Amato
cond-mat.str-el