Dynamical spin response of electron doped Mott insulators on a triangular lattice

The spin dynamics of electron doped Mott insulators on a triangular lattice is studied based on the t–Jt–J model. It is found that the particularly universal behaviors of integrated dynamical spin structure factor seen in the doped Mott insulators on a square lattice, are absent in the doped Mott insulators on a triangular lattice, indicating the presence of the normal state gap. As a result, the spin–lattice relaxation rate 1/T11/T1 divided by TT reduces with decreasing temperatures in the temperature region above 0.2J≈50K, then follows a Curie–Weiss-like behavior at the temperature less than 50 K, in qualitative agreement with experimental observations.

► A deviation from a universal behavior was shown in temperature dependence of dynamical spin structure factor.
► A weak normal state gap caused by spin frustration was found.
► Spin–lattice relaxation reproduces the experimental observation, and was explained by anomalous spin dynamics.