Category: News

Magnetic reversal in perpendicularly magnetized antidot arrays with intrinsic and extrinsic defects

Defects can significantly affect performance of nanopatterned magnetic devices, therefore their influence on the material properties has to be understood well before the material is used in technological applications. However, this is experimentally challenging due to the inability of the control of defect characteristics in a reproducible manner.*

In “Magnetic reversal in perpendicularly magnetized antidot arrays with intrinsic and extrinsic defects» Michal Krupinski, Pawel Sobieszczyk, Piotr Zieliński and Marta Marszałek construct a micromagnetic model, which accounts for intrinsic and extrinsic defects associated with the polycrystalline nature of the material and with corrugated edges of nanostructures.*

The findings described in their article show that magnetic properties and domain configuration in nanopatterned systems are strongly determined by the defects, the heterogeneity of the nanostructure sizes and edge corrugations, and that such imperfections play a key role in the processes of magnetic reversal.*

The magnetic imaging described in the article cited above was performed using NanoWorld MFMR AFM probes for magnetic force microscopy (MFMR).

Figure 8 from “Magnetic reversal in perpendicularly magnetized antidot arrays with intrinsic and extrinsic defects” by Michal Krupinski et al.: (a) MFM image for an array with an antidot diameter 182 nm taken in zero field after ac demagnetization. Selected domain walls were marked with a blue line. (b) Simulated MFM image for an antidot diameter of 185 nm corresponding to the magnetic moment configuration depicted in Fig. 6b. The MFM tip distance from the sample surface was 180 nm.
Figure 8 from “Magnetic reversal in perpendicularly magnetized antidot arrays with intrinsic and extrinsic defects” by Michal Krupinski et al.:
(a) MFM image for an array with an antidot diameter 182 nm taken in zero field after ac demagnetization. Selected domain walls were marked with a blue line. (b) Simulated MFM image for an antidot diameter of 185 nm corresponding to the magnetic moment configuration depicted in Fig. 6b. The MFM tip distance from the sample surface was 180 nm.

*Michal Krupinski, Pawel Sobieszczyk, Piotr Zieliński and Marta Marszałek
Magnetic reversal in perpendicularly magnetized antidot arrays with intrinsic and extrinsic defects
Nature Scientific Reports volume 9, Article number: 13276 (2019)
DOI: https://doi.org/10.1038/s41598-019-49869-5

Please follow this external link to read the full article https://rdcu.be/bYXYP

Open Access: The article “Magnetic reversal in perpendicularly magnetized antidot arrays with intrinsic and extrinsic defects” by Michal Krupinski, Pawel Sobieszczyk, Piotr Zieliński and Marta Marszałek 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/.

Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly

Ferroelectric memories are endowed with high data storage density by nanostructure designing, while the robustness is also impaired. For organic ferroelectrics favored by flexible memories, low Curie transition temperature limits their thermal stability.*

In their article “Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly “ Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan and Yang Shen demonstrate that a ferroelectric random access memory ( FeRAM ) with high thermal stability and data storage density of ≈60 GB inch−2 could be achieved from an array of edge‐on nano‐lamellae by low‐temperature self‐assembly of P(VDF‐TrFE).*

The self‐assembled P(VDF‐TrFE) described in the article exhibits high storage density of 60 GB inch−2 as a prototype of flexible FeRAM. The authors experimentally determine the self‐assembled FeRAM stored data more robustly, with temperature endurance enhanced over 10 °C and reliable thermal cycling ability. The article shows a novel path to address the thermal stability issues in organic FeRAMs and presents a detailed analysis about the origin of enhanced performance in aligned P(VDF‐TrFE). *

NanoWorld Arrow-CONTPt AFM probes with a conducting Pt/Ir coating were used for the Piezoresponse Force Microscopy ( PFM ) measurements described in this article.

Figure 4 from “Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly” by Mengfan Guo et al.:
Enhanced thermal stability in SA P(VDF‐TrFE). a–c) PFM images of data stored in self‐assembled film at a) 25 °C and b) 90 °C, as well as c) numeric figure of residual area of reversal domains as a function of elevated temperature in a SA film (blue) and a NSA film (red). d) Numeric figure of residual area of reversal domains as a function of thermal cycles in a SA film (blue) and a NSA film (red). Scale bars: 200 nm.

*Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan, Yang Shen
Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly
Advanced Science, Volume6, Issue6, March 20, 2019, 1801931
DOI: https://doi.org/10.1002/advs.201801931

Please follow this external link to read the full article: https://onlinelibrary.wiley.com/doi/full/10.1002/advs.201801931

Open Access: The article « Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly » by Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan and Yang Shen 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/.

Cellulose carbamate derived cellulose thin films: preparation, characterization and blending with cellulose xanthate

Despite being rather old, the Viscose process still is the most important and frequently used technology for the production of regenerated wood based fibers with annual production volumes exceeding 3.5 million tons, mainly for the textile industry.*

However, there are several environmental drawbacks of this technology. For instance, the necessity to use CS2 to form the cellulose precursor material (cellulose xanthate, CX), as well as the development of volatile sulfur containing compounds (e.g. H2S, COS) during the regeneration procedure requires complex recovery technologies, which manifest into higher prices of the final fiber products.*

Another technology that has raised attention in recent years is the Carbacell process. The Carbacell process relies on cellulose carbamate (CC), which is easily obtained by reacting cellulose with urea. CC is soluble in cold alkali and can be subjected to wet spinning processes similar to those in viscose plants.*

In their article: “Cellulose carbamate derived cellulose thin films: preparation, characterization and blending with cellulose xanthate” Michael Weißl, Mathias Andreas Hobisch, Leena Sisko Johansson, Kay Hettrich, Eero Kontturi, Bert Volkert and Stefan Spirk introduce a new system for manufacturing cellulose thin films based on ecofriendly CC. *

Since CC is water soluble, the use of organic solvents is omitted compared to the other often employed cellulose derivative, TMSC. In addition, CC can be synthesized in large scale via environmentally friendly procedures. The regeneration process itself does not require any additional treatment but is induced by increasing the NaOH concentration during the spin-coating via evaporation of the water, as confirmed by IR and XPS spectroscopy.*

Atomic Force Microscopy in tapping mode using a NanoWorld Arrow-NCR AFM probe was employed to gain further information about the surface morphology and structure of the CC films.

Fig. 3 from “Cellulose carbamate derived cellulose thin films: preparation, characterization and blending with cellulose xanthate” by Michael Weißl et al.:
2 × 2 µm2 AFM height (upper row) and phase (lower row) images of CC based thin films after spin coating and rinsing with water; starting with concentrations from 1.0 to 1.5, 2.0 and 2.5 wt%

*Michael Weißl, Mathias Andreas Hobisch, Leena Sisko Johansson, Kay Hettrich, Eero Kontturi, Bert Volkert, Stefan Spirk
Cellulose carbamate derived cellulose thin films: preparation, characterization and blending with cellulose xanthate
Cellulose, August 2019, Volume 26, Issue 12, pp 7399–7410
Doi: https://doi.org/10.1007/s10570-019-02600-z

Please follow this external link to read the full article: https://link.springer.com/article/10.1007%2Fs10570-019-02600-z

Open Access: The paper « Cellulose carbamate derived cellulose thin films: preparation, characterization and blending with cellulose xanthate » by Michael Weißl, Mathias Andreas Hobisch, Leena Sisko Johansson, Kay Hettrich, Eero Kontturi, Bert Volkert and Stefan Spirk 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/.