Tag Archives: PPP-EFM

Ferroelectricity-free lead halide perovskites

In the recent publication “Ferroelectricity-free lead halide perovskites” Andrés Gómez, Qiong Wang, Alejandro R. Goñi, Mariano Campoy-Quilesa and Antonio Abate describe how they employed direct piezoelectric force microscopy ( DPFM ) to examine whether or not lead halide perovskites exhibit ferroelectricity.*

Their article aims to provide a deeper understanding of the fundamental physical properties of the organic–inorganic lead halide perovskites and solves a longstanding dispute about their non-ferroelectric character: an issue of high relevance for optoelectronic and photovoltaic applications.*

In the course of their research in which besides using DPFM, they also employed piezoelectric force microscopy ( PFM ) and electrostatic force microscopy ( EFM ), they could demonstrate the non-ferroelectricity of lead halide perovskites. *

The PFM images were acquired using a PtIr coated NANOSENSORS PPP-EFM AFM probe.

Fig. 5 from “Ferroelectricity-free lead halide perovskites” by Andrés Gómez et al.: Scheme of the three AFM modes DPFM (a), EFM (b) and PFM (c) with the measurement results of the MAPbI3 perovskite at a film thickness of 152 nm ((i): scanning from left to right, and (ii): scanning from right to left for DPFM measurements; and (iii) and (iv) for EFM and PFM measurements, respectively), 218 nm ((v): scanning from left to right, and (vi): scanning from right to left for DPFM measurements; and (vii) and (viii) for EFM and PFM measurements, respectively), and 400 nm ((ix): scanning from left to right, and (x): scanning from right to left for DPFM measurements; and (xi) and (xii) for EFM and PFM measurements, respectively). Insets given in (iii), (vii), and (xi) are the topography channel of EFM images of the samples.

*Andrés Gómez, Qiong Wang, Alejandro R. Goñi, Mariano Campoy-Quilesa, Antonio Abate
Ferroelectricity-free lead halide perovskites
Energy Environ. Sci., 2019, Advance Article
doi: 10.1039/C9EE00884E

Please follow this external link to the full article: https://pubs.rsc.org/en/content/articlelanding/2019/ee/c9ee00884e#!divAbstract

Open Access: The article “Ferroelectricity-free lead halide perovskites” by Andrés Gómez, Qiong Wang, Alejandro R. Goñi, Mariano Campoy-Quilesa and Antonio Abate is licensed under a Creative Commons Attribution 3.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. To view a copy of this license, visit https://creativecommons.org/licenses/by/3.0/

Optical control of polarization in ferroelectric heterostructures

“In the ferroelectric devices, polarization control is usually accomplished by application of an electric field.”* In the article “Optical control of polarization in ferroelectric heterostructures” Tao Li et al. demonstrate optically induced polarization switching in BaTiO3-based ferroelectric heterostructures utilizing a two-dimensional narrow-gap semiconductor MoS2 as a top electrode. NANOSENSORS PPP-EFM PtIr coated AFM probes were used to perform the KPFM and PFM measurements mentioned in the article cited below.
Figure 1 from “Optical control of polarization in ferroelectric heterostructures”: Electrically induced polarization switching in the MoS2/BaTiO3/SrRuO3 junction. a, b PFM phase (a) and amplitude (b) images after application of a negative voltage pulse (−5 V, 0.5 s) to the MoS2 flake. The 12-u.c.-thick BTO film underneath the MoS2 flake is fully switched to the upward polarization, Pup. c, d PFM phase (c) and amplitude (d) images after application of several positive voltage pulses (+5 V, 0.5 s) to the MoS2 flake. BTO underneath the MoS2 flake is fully switched to downward polarization, Pdown. The polarization state of the bare BTO film (at the lower right corner) is not affected by the electrical bias. e, f The I–V characteristics of the same junction measured in the dark and during illumination. The tunneling current for the OFF state (Pup) is largely increased under illumination. Silicon AFM probes with Pt/Ir conductive coating and nominal stiffness of 3 N m−1 (PPP-EFM, NANOSENSORS) were used to perform the KPFM and PFM measurements.
Figure 1 from “Optical control of polarization in ferroelectric heterostructures”:
Electrically induced polarization switching in the MoS2/BaTiO3/SrRuO3 junction. a, b PFM phase (a) and amplitude (b) images after application of a negative voltage pulse (−5 V, 0.5 s) to the MoS2 flake. The 12-u.c.-thick BTO film underneath the MoS2 flake is fully switched to the upward polarization, Pup. c, d PFM phase (c) and amplitude (d) images after application of several positive voltage pulses (+5 V, 0.5 s) to the MoS2 flake. BTO underneath the MoS2 flake is fully switched to downward polarization, Pdown. The polarization state of the bare BTO film (at the lower right corner) is not affected by the electrical bias. e, f The I–V characteristics of the same junction measured in the dark and during illumination. The tunneling current for the OFF state (Pup) is largely increased under illumination
*Tao Li, Alexey Lipatov, Haidong Lu, Hyungwoo Lee, Jung-Woo Lee, Engin Torun, Ludger Wirtz, Chang-Beom Eom, Jorge Íñiguez, Alexander Sinitskii, Alexei Gruverman Optical control of polarization in ferroelectric heterostructures Nature Communications, volume 9, Article number: 3344 (2018) DOI: https://doi.org/10.1038/s41467-018-05640-4 Please follow this external link to read the full article: https://rdcu.be/bdFYw Open Access:  The article “Optical control of polarization in ferroelectric heterostructures” by Tao Li et. Al. is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Injection and controlled motion of conducting domain walls in improper ferroelectric Cu-Cl boracite

NANOSENSORS PPP-EFM AFM tips were used in the research for this article. Have a look at the abstract or follow the external link to the full article.

Figure 1: Crystal structure and domains in boracites. From: Injection and controlled motion of conducting domain walls in improper ferroelectric Cu-Cl boracite
Figure 1: Crystal structure and domains in boracites.
From: Injection and controlled motion of conducting domain walls in improper ferroelectric Cu-Cl boracite

Raymond G.P. McQuaid, Michael P. Campbell, Roger W. Whatmore, Amit Kumar, J. Marty Gregg
Injection and controlled motion of conducting domain walls in improper ferroelectric Cu-Cl boracite. Nat. Commun. 8, 15105 doi: 10.1038/ncomms15105 (2017).

Abstract:
Ferroelectric domain walls constitute a completely new class of sheet-like functional material. Moreover, since domain walls are generally writable, erasable and mobile, they could be useful in functionally agile devices: for example, creating and moving conducting walls could make or break electrical connections in new forms of reconfigurable nanocircuitry. However, significant challenges exist: site-specific injection and annihilation of planar walls, which show robust conductivity, has not been easy to achieve. Here, we report the observation, mechanical writing and controlled movement of charged conducting domain walls in the improper-ferroelectric Cu3B7O13Cl. Walls are straight, tens of microns long and exist as a consequence of elastic compatibility conditions between specific domain pairs. We show that site-specific injection of conducting walls of up to hundreds of microns in length can be achieved through locally applied point-stress and, once created, that they can be moved and repositioned using applied electric fields.

Please follow this external link for the full article: https://www.nature.com/articles/ncomms15105

Creative Commons BYThe article “Injection and controlled motion of conducting domain walls in improper ferroelectric Cu-Cl boracite” by McQuaid, R. G. P. et al. is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/