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Dipolar Order Controls Dielectric Response of Glass-Forming Liquids
Till Böhmer1, Florian Pabst1,2, Jan P Gabriel3,4
1Institute for Condensed Matter Physics, Technical University of Darmstadt, D-64289 Darmstadt, Germany.
Physical Review Letters
|June 3, 2024
Summary
In supercooled liquids, the dielectric loss exponent (β) correlates with dipolar order (Kirkwood correlation factor gK). This finding supports new theories but contradicts the earlier Kivelson-Madden theory.
Area of Science:
- Dielectric spectroscopy
- Condensed matter physics
- Physical chemistry
Background:
- The dielectric response of liquids involves single molecule reorientation and collective dipolar cross-correlations.
- A recent theory predicts collective modes create a slow peak in dielectric loss spectra.
Purpose of the Study:
- To investigate the correlation between the high-frequency dielectric loss exponent (β) and the Kirkwood correlation factor (gK) in supercooled liquids.
- To test the predictions of recent theories on dielectric response and dipolar order.
Main Methods:
- Analysis of dielectric loss spectra for 25 supercooled liquids.
- Calculation of the high-frequency power law exponent (β).
- Determination of the Kirkwood correlation factor (gK) to quantify dipolar order.
Main Results:
- A significant correlation was confirmed between the dielectric loss exponent (β) and the Kirkwood correlation factor (gK) across 25 supercooled liquids.
- The findings support recent theoretical predictions regarding collective modes and dielectric response.
- The results were found to contradict the predictions of the earlier Kivelson-Madden theory.
Conclusions:
- The degree of dipolar order in supercooled liquids, quantified by gK, is intrinsically linked to their high-frequency dielectric loss behavior (β).
- This study validates recent theoretical advancements in understanding liquid dielectric properties.
- The established correlation challenges and potentially refutes the applicability of the Kivelson-Madden theory to these systems.
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