Published online by Cambridge University Press: 01 February 2011
In Ultrasonic Force Microscopy, the mechanical diode response refers to the quasistatic cantilever deflexion in the presence of surface out-of-plane ultrasonic vibration of sufficiently high amplitude. The effect has been described by introducing ultrasonic-amplitude-dependent tip-sample force-distance curves [Phys. Rev. 61 (2000) 13997]. Here, we demonstrate that the ultrasonic hysteresis phenomenon is qualitatively explained taking into account that for certain ultrasonic amplitudes, the modified tip-sample forces lead to two stable quasi-static equilibrium states, separated by an energy barrier. Experimental UFM data obtained on mica at ambient conditions are discussed in terms of ultrasonic-induced quasi-static equilibrium states, taking into account the role of the surface water layer.