Experimental percolation studies of two-dimensional honeycomb lattice: Li₂Mn_1-xTi_xO3

Li₂MnO₃with a S = 3/2 two-dimensional Mn honeycomb lattice has a Neel-type antiferromagnetic transition at T_N= 36 K with a broad maximum in magnetic susceptibility at T_M= 48 K. We have investigated site percolation effects by replacing Mn with nonmagnetic Ti, and completed a full phase diagram of Li₂Mn₁-xTi _xO₃solid solution systems to find that antiferromagnetic transition is continuously suppressed without a clear sign of changes in the Neel-type antiferromagnetic structure. The magnetic ordering eventually disappears at a critical concentration of x_c= 0.7. This experimental observation is consistent with percolation theories for a honeycomb lattice when one considers up to 3rd nearest-neighbor interactions. This study highlights the importance of interaction beyond nearest neighbors even for the Mn element with relative localized 3d electrons in the honeycomb lattice.