IMF2017

Polarization switching in ferroelectric and multiferroic materials forms the basis for the next generation of electronic devices such as race-track memories, field effect transistors, and tunneling devices. The switching mechanisms in these materials are highly sensitive to the local defects and structural imperfections at the nanometer scale which in-turn have undesirable effects on ferroelectric domains. These considerations necessitated the development of Piezoresponse Force Microscopy (PFM) techniques to measure and manipulate local polarization states. However, the current state-of-art PFM spectroscopy techniques suffer from serious compromises in the measurement speed, voltage and spatial resolutions since they typically combine a slow (~1 sec) switching signal with a fast (~1 – 10 msec) measurement signal. Moreover, transients in the cantilever response at higher vibrational modes and harmonics are lost since the signal from only a single, or a narrow band of frequencies is typically acquired. We report on a fundamentally new approach that combines the complete acquisition of the cantilever response signal with data-driven signal filtering techniques to directly measure material strain in response to the probing bias. Our technique, called General mode Voltage Spectroscopy (G-VS), enables precise spectroscopic imaging of the polarization switching phenomena 3,500 times faster than currently reported methods. Rapid acquisition of large numbers of hysteretic loops on very dense grids will enable significant insight into nanoscale polarization dynamics and phenomena such as polarization fatigue and local wall displacements that remain difficult to study at the desired spatial and temporal scales, which are crucial for developing future electronic devices.