What is DFRT-PFM
DFRT-PFM is an advanced piezoresponse imaging technique developed by Park Systems to overcome the limitations of conventional PFM. By using two frequencies for resonance tracking and another for actual piezoresponse detection, DFRT-PFM maintains stable, high-sensitivity measurements even as the resonance conditions change. This enables precise visualization and analysis of complex domain structures, polarization switching, and local electromechanical responses in a wide range of functional materials.
Reasons to Use This Mode
For a technical comparison between DFRT PFM and conventional PFM techniques, like Off resonance-PFM (OR-PFM) and Contact resonance-PFM (CR-PFM), measurements were carried out on the same region of the CuInP₂S₆ (CIPS) sample using consistent experimental parameters. The collected datasets consist of surface topography (height channel) along with vertical PFM amplitude and phase images from each method. DFRT PFM provides high-resolution feature delineation with minimal lateral noise. Conversely, conventional techniques display lateral noise artifacts, and OR-PFM notably fails to resolve many features. In the boxed regions of the images, a diagonal boundary—present in both topography and CR-PFM—is nearly indistinguishable in OR-PFM data. Such artifacts complicate accurate differentiation of true piezoresponse signals from topographic crosstalk, especially when the domain structure is unknown, potentially compromising data interpretation.
Height
- Sample: CuInP₂S₆ (CIPS)
- System: FX40
- Scan Size: 3 µm × 3 µm
DFRT-PFM Amplitude
CR-PFM Amplitude
OR-PFM Amplitude
DFRT-PFM Phase
CR-PFM Phase
OR-PFM Phase
| DFRT-PFM | CR-PFM | OR-PFM |
| Frequency Range
Real-time tracking using dual frequencies for resonance compensation |
Frequency Range
Near contact resonance (~3–5× free resonance) |
Frequency Range
Low frequency, far from cantilever resonance |
| Topographic Crosstalk
Significantly reduced by resonance tracking feedback |
Topographic Crosstalk
Higher due to resonance shifts causing crosstalk |
Topographic Crosstalk
Minimal, but weaker signals prone to noise |
| Signal Stability
Very stable → automatic real-time resonance frequency adjustment |
Signal Stability
Unstable → sensitive to tip-sample contact variations |
Signal Stability
Relatively stable but noisy |
| Suitable Samples
Weak piezoresponse, rough surfaces |
Suitable Samples
Samples with weak piezoresponse needing signal boost |
Suitable Samples
Samples with strong piezoresponse |
| Key Advantages
High accuracy, stable signals, simultaneous vertical & lateral tracking |
Key Advantages
Strong signal, straightforward single-frequency method |
Key Advantages
Simple setup, low topographic interference |
Applications and Use Cases
A PMN-PT single crystal was measured using DFRT-PFM to demonstrate simultaneous vertical and lateral piezoresponse imaging. Vertical and lateral cantilever displacements were obtained through separate input channels and lock-in amplifiers, with independent AC voltages applied at each resonance frequency and sideband feedback loops engaged for real-time resonance tracking. Clear domain walls were visualized in both channels with minimal topographic crosstalk. Distinct lateral PFM amplitude patterns were observed relative to the vertical channel, indicating reliable detection of in-plane electromechanical response and confirming robust DFRT-PFM performance for PMN-PT characterization.
Z Height
- Sample: PMN-PT
- System: FX40
- Scan Size: 10 µm × 10 µm
PFM Amplitude
PFM Amplitude
PFM Phase
