Spin decoherence processes in the S=1/2 scalene triangular cluster (Cu3(OH))

We report the synthesis and magnetic properties of the molecular cluster Cu3(μ3−OH)(μ-OH)(μ-O2Ar4F-Ph)2(py)3(OTf)2, abbreviated as (Cu3(OH)). Using magnetization, electron paramagnetic resonance and spin dimer analysis, we derive a microscopic magnetic model of (Cu3(OH)) and measure the electron T1 and T2 relaxation times. The Cu2+ ions are arranged to form a distorted triangular structure with the three different exchange coupling constants J1 = −43.5 K, J2 = −53.0 K, and J3 = −37.7 K. At T = 1.5 K T1 is of the order of 10−4 s and T2 is evaluated to be 0.26 μs. We find that the temperature dependence of 1/T1 and 1/T2 is governed by Orbach process and spin bath fluctuations, respectively. We discuss the role of spin–phonon mechanism in determining a spin decoherence time in a class of spin triangular clusters.