Intermode coupling in nanomechanical resonators as a key for tuning the effective nonlinearity

Nonlinear interaction of flexural and torsional modes is experimentally studied in a cantileverlike nanomechanical resonator. The resonant frequency of each mode depends much weaker on its own amplitude than on the amplitude of another mode. This property makes it possible to widely tune the effective nonlinearity of each mode on chip, making the same system exhibit hardening, softening, or linear behavior. This nonlinear tuning in one mode is achieved by adjusting the driving frequency and amplitude of the other mode. It is shown that this effective tunability may be characteristic of resonators with a high width-to-thickness ratio.