Imperial College London
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ProfessorRogerWhatmore

Faculty of Engineering, Department of Materials

Visiting Professor
 
 
 
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Contact

 

r.whatmore

 
 
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Location

 

Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Guy:2021:10.1002/adma.202008068,
author = {Guy, JGM and Cochard, C and Aguado-Puente, P and Soergel, E and Whatmore, RW and Conroy, M and Moore, K and Courtney, E and Harvey, A and Bangert, U and Kumar, A and McQuaid, RGP and Gregg, JM},
doi = {10.1002/adma.202008068},
journal = {Advanced Materials},
pages = {1--10},
title = {Anomalous motion of charged domain walls and associated negative capacitance in copper-chlorine boracite.},
url = {http://dx.doi.org/10.1002/adma.202008068},
volume = {33},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - During switching, the microstructure of a ferroelectric normally adapts to align internal dipoles with external electric fields. Favorably oriented dipolar regions (domains) grow at the expense of those in unfavorable orientations and this is manifested in a predictable field-induced motion of the walls that separate one domain from the next. Here, the discovery that specific charged 90°domain walls in copper-chlorine boracite move in the opposite direction to that expected, increasing the size of the domain in which polarization is anti-aligned with the applied field, is reported. Polarization-field (P-E) hysteresis loops, inferred from optical imaging, show negative gradients and non-transient negative capacitance, throughout the P-E cycle. Switching currents (generated by the relative motion between domain walls and sensing electrodes) confirm this, insofar as their signs are opposite to those expected conventionally. For any given bias, the integrated switching charge due to this anomalous wall motion is directly proportional to time, indicating that the magnitude of the negative capacitance component should be inversely related to frequency. This passes Jonscher's test for the misinterpretation of positive inductance and gives confidence that field-induced motion of these specific charged domain walls generates a measurable negative capacitance contribution to the overall dielectric response.
AU  - Guy,JGM
AU  - Cochard,C
AU  - Aguado-Puente,P
AU  - Soergel,E
AU  - Whatmore,RW
AU  - Conroy,M
AU  - Moore,K
AU  - Courtney,E
AU  - Harvey,A
AU  - Bangert,U
AU  - Kumar,A
AU  - McQuaid,RGP
AU  - Gregg,JM
DO  - 10.1002/adma.202008068
EP  - 10
PY  - 2021///
SN  - 0935-9648
SP  - 1
TI  - Anomalous motion of charged domain walls and associated negative capacitance in copper-chlorine boracite.
T2  - Advanced Materials
UR  - http://dx.doi.org/10.1002/adma.202008068
UR  - https://www.ncbi.nlm.nih.gov/pubmed/33734520
UR  - https://onlinelibrary.wiley.com/doi/10.1002/adma.202008068
UR  - http://hdl.handle.net/10044/1/87707
VL  - 33
ER  -
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