Robust Spin Liquidity in 2D Metal‐Organic Framework Cu3 (HHTP)2 with S=1/2 Kagome Lattice

Abstract On one hand electron or hole doping of quantum spin liquid (QSL) may unlock high‐temperature superconductivity and on the other hand it can disrupt the spin liquidity, giving rise to a magnetically ordered ground state. Recently, a 2D MOF, Cu3(HHTP)2 (HHTP ‐ 2,3,6,7,10,11‐hexahydroxytriphenylene), containing Cu(II) S= frustrated spins in the Kagome lattice is emerging as a promising QSL candidate. Herein, we present an elegant in situ redox‐chemistry strategy of anchoring Cu3(HHTP)2 crystallites onto diamagnetic reduced graphene oxide (rGO) sheets, resulting in the formation of electron‐doped Cu3(HHTP)2‐rGO composite which exhibited a characteristic semiconducting behavior (5 K to 300 K) with high electrical conductivity of 70 S ⋅ m−1 and a carrier density of ~1.1×1018 cm−3 at 300 K. Remarkably, no magnetic transition in the Cu3(HHTP)2‐rGO composite was observed down to 1.5 K endorsing the robust spin liquidity of the 2D MOF Cu3(HHTP)2. Specific heat capacity measurements led to the estimation of the residual entropy values of 28 % and 34 % of the theoretically expected value for the pristine Cu3(HHTP)2 and Cu3(HHTP)2‐rGO composite, establishing the presence of strong quantum fluctuations down to 1.5 K (two times smaller than the value of the exchange interaction J).