Study of the exotic quantum magnetic state in paratacamite

Since the discovery of spin-liquid behaviors in herbertsmithite ZnCu3(OH)6Cl2, thousands of papers have been published on this subject. However, it remains an open issue about the intrinsic nature of the ground state in herbertsmithite, because ZnCu3(OH)6Cl2 was obtained by substituting Cu2(OH)3Cl [or exprssed as Cu4(OH)6Cl2] and inevitably contained a lot of defects. Previously we found unconventional magnetic transitions and coexistence of order and spin fluctuations in clinoatacamite, Cu2(OH)3Cl [2005 Phys. Rev. Lett. 95 057201], which was the parent compound of herbertsmithite [ZnCu3(OH)6Cl2, which was obtained by substituting Cu with non-magnetic Zn]. Fortunately, now we succeeded in synthesizing single crystals of paratacamite Cu2(OH)3Cl which is a polymorphous structure to clinoatacamite but with high symmetry like herbertsmithite. It is the optimum compound to study with muSR.