Tag Archives: MFM tips

Electric-field-driven non-volatile multi-state switching of individual skyrmions in a multiferroic heterostructure

Electrical manipulation of skyrmions attracts considerable attention for its rich physics and promising applications. To date, such a manipulation is realized mainly via spin-polarized current based on spin-transfer torque or spin–orbital torque effect.*

However, this scheme is energy consuming and may produce massive Joule heating. To reduce energy dissipation and risk of heightened temperatures of skyrmion-based devices, an effective solution is to use electric field instead of current as stimulus.*

In the article “Electric-field-driven non-volatile multi-state switching of individual skyrmions in a multiferroic heterostructure”, Yadong Wang, Lei Wang, Jing Xia, Zhengxun Lai, Guo Tian, Xichao Zhang, Zhipeng Hou, Xingsen Gao, Wenbo Mi, Chun Feng, Min Zeng, Guofu Zhou, Guanghua Yu, Guangheng Wu, Yan Zhou, Wenhong Wang, Xi-xiang Zhang and Junming Liu realize an electric-field manipulation of skyrmions in a nanostructured ferromagnetic/ferroelectrical heterostructure at room temperature via an inverse magneto-mechanical effect.*

Intriguingly, such a manipulation is non-volatile and exhibits a multistate feature. Numerical simulations indicate that the electric-field manipulation of skyrmions originates from strain-mediated modification of effective magnetic anisotropy and Dzyaloshinskii–Moriya interaction.*

The results presented in the article open a direction for constructing low-energy-dissipation, non-volatile, and multistate skyrmion-based spintronic devices.*

To minimize the influence of the magnetic field from the MFM tip on the magnetic domain structure during the magnetic force microscopy ( MFM ) measurements, NANOSENSORS™ PPP-LM-MFMR low moment magnetic AFM probes were used.*

These MFM probes are designed for magnetic force microscopy with reduced disturbance of the magnetic sample by the tip and enhanced lateral resolution compared to the standard PPP-MFMR probe. The distance between the tip and sample was maintained at a constant distance of 30 nm.*

Figure 2 from “Electric-field-driven non-volatile multi-state switching of individual skyrmions in a multiferroic heterostructure” by Yadong Wang et al.:
Electric-field-induced switching of individual skyrmion.
The transferred average strain εave and corresponding magnetic domain evolution processes in the d ~ 350 nm a [Pt/Co/Ta]12 and b [Pt/Co/Ta]8 nano-dots in a cycle of E ranging from +10 to −10 kV cm−1. Positive εave (red dots) represents tensile strain while negative εave (blue dots) represents compressive strain. μ0H represents the external magnetic field except that from the MFM tip and here μ0H is equal to be 0 mT. The inset of b illustrates the spin texture of the magnetic domain that is encompassed by the red box. The stripe domain enclosed by the black box shows the initial state of the magnetic domain evolution path. The gray dots represent the corresponding electric field for the MFM images. The MFM contrast represents the MFM tip resonant frequency shift (Δf). The scale bar represents 250 nm.

NANOSENSORS™ PPP-LM-MFMR low moment magnetic AFM probes were used
Figure 2 from “Electric-field-driven non-volatile multi-state switching of individual skyrmions in a multiferroic heterostructure” by Yadong Wang et al.:
Electric-field-induced switching of individual skyrmion.
The transferred average strain εave and corresponding magnetic domain evolution processes in the d ~ 350 nm a [Pt/Co/Ta]12 and b [Pt/Co/Ta]8 nano-dots in a cycle of E ranging from +10 to −10 kV cm−1. Positive εave (red dots) represents tensile strain while negative εave (blue dots) represents compressive strain. μ0H represents the external magnetic field except that from the MFM tip and here μ0H is equal to be 0 mT. The inset of b illustrates the spin texture of the magnetic domain that is encompassed by the red box. The stripe domain enclosed by the black box shows the initial state of the magnetic domain evolution path. The gray dots represent the corresponding electric field for the MFM images. The MFM contrast represents the MFM tip resonant frequency shift (Δf). The scale bar represents 250 nm.

*Yadong Wang, Lei Wang, Jing Xia, Zhengxun Lai, Guo Tian, Xichao Zhang, Zhipeng Hou, Xingsen Gao, Wenbo Mi, Chun Feng, Min Zeng, Guofu Zhou, Guanghua Yu, Guangheng Wu, Yan Zhou, Wenhong Wang, Xi-xiang Zhang and Junming Liu
Electric-field-driven non-volatile multi-state switching of individual skyrmions in a multiferroic heterostructure
Nature Communications volume 11, Article no. 3577 (2020)
DOI: https://doi.org/10.1038/s41467-020-17354-7

Please follow this external link to read the full article: https://rdcu.be/b6qpr

Open Access: The article “Electric-field-driven non-volatile multi-state switching of individual skyrmions in a multiferroic heterostructure” by Yadong Wang, Lei Wang, Jing Xia, Zhengxun Lai, Guo Tian, Xichao Zhang, Zhipeng Hou, Xingsen Gao, Wenbo Mi, Chun Feng, Min Zeng, Guofu Zhou, Guanghua Yu, Guangheng Wu, Yan Zhou, Wenhong Wang, Xi-xiang Zhang and Junming Liu 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/.

Observation of a gel of quantum vortices in a superconductor at very low magnetic fields

A gel consists of a network of particles or molecules formed for example using the sol-gel process, by which a solution transforms into a porous solid. Particles or molecules in a gel are mainly organized on a scaffold that makes up a porous system. Quantized vortices in type-II superconductors mostly form spatially homogeneous ordered or amorphous solids.*

In the article “Observation of a gel of quantum vortices in a superconductor at very low magnetic fields” José Benito Llorens, Lior Embon, Alexandre Correa, Jesús David González, Edwin Herrera, Isabel Guillamón, Roberto F. Luccas, Jon Azpeitia, Federico J. Mompeán, Mar García-Hernández, Carmen Munuera, Jazmín Aragón Sánchez, Yanina Fasano, Milorad V. Milošević, Hermann Suderow and Yonathan Anahory present high-resolution imaging of the vortex lattice displaying dense vortex clusters separated by sparse or entirely vortex-free regions in β−Bi2Pd superconductor.*

The authors find that the intervortex distance diverges upon decreasing the magnetic field and that vortex lattice images follow a multifractal behavior. These properties, characteristic of gels, establish the presence of a novel vortex distribution, distinctly different from the well-studied disordered and glassy phases observed in high-temperature and conventional superconductors.*

The observed behavior is caused by a scaffold of one-dimensional structural defects with enhanced stress close to the defects. The vortex gel might often occur in type-II superconductors at low magnetic fields. Such vortex distributions should allow to considerably simplify control over vortex positions and manipulation of quantum vortex states.*

The results presented in the article show that vortices are nearly independent to each other at very low magnetic fields and that their position is locked to the defect structure in the sample. This suggests that vortices in this field range are also highly manipulable, much more than in usual hexagonal or disordered vortex lattices.

The magnetic force microscopy (MFM) measurements described in the article were performed in a commercial Low-Temperature  SPM equipment working in the 300–1.8  K temperature range using NANOSENSORS magnetic AFM probes of the type PPP-MFMR that were magnetized prior to the measurement by applying a magnetic field of 1500 G at 10 K.

figure 8 from “Observation of a gel of quantum vortices in a superconductor at very low magnetic fields” by José Benito Llorens et al.:
Behavior of the hexagonal vortex lattice as a function of temperature measured with MFM. In (a)–(c), the images are taken at 2.75,3.75, and 4.5 K, respectively at 300 G. The color scale represents the observed frequency shift. Scale bar is 1μm. Blue lines are the Delaunay triangulation of vortex positions. Blue and red points in (a) highlight vortices with seven and five nearest neighbors respectively. The dark arrow at the bottom highlights the position of the vertical line discussed in the text.
figure 8 from “Observation of a gel of quantum vortices in a superconductor at very low magnetic fields” by José Benito Llorens et al.:
Behavior of the hexagonal vortex lattice as a function of temperature measured with MFM. In (a)–(c), the images are taken at 2.75,3.75, and 4.5 K, respectively at 300 G. The color scale represents the observed frequency shift. Scale bar is 1μm. Blue lines are the Delaunay triangulation of vortex positions. Blue and red points in (a) highlight vortices with seven and five nearest neighbors respectively. The dark arrow at the bottom highlights the position of the vertical line discussed in the text.

*José Benito Llorens, Lior Embon, Alexandre Correa, Jesús David González, Edwin Herrera, Isabel Guillamón, Roberto F. Luccas, Jon Azpeitia, Federico J. Mompeán, Mar García-Hernández, Carmen Munuera, Jazmín Aragón Sánchez, Yanina Fasano, Milorad V. Milošević, Hermann Suderow, and Yonathan Anahory
Observation of a gel of quantum vortices in a superconductor at very low magnetic fields
Physical Review Research 2, 013329 (2020)
DOI:10.1103/PhysRevResearch.2.013329

Please follow this external link to read the full article: https://journals.aps.org/prresearch/pdf/10.1103/PhysRevResearch.2.013329

Open Access: The article “Observation of a gel of quantum vortices in a superconductor at very low magnetic fields” by José Benito Llorens, Lior Embon, Alexandre Correa, Jesús David González, Edwin Herrera, Isabel Guillamón, Roberto F. Luccas, Jon Azpeitia, Federico J. Mompeán, Mar García-Hernández, Carmen Munuera, Jazmín Aragón Sánchez, Yanina Fasano, Milorad V. Milošević, Hermann Suderow, and Yonathan Anahory 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/.

From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies

In their research paper “From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies” Federico Cesano, Sara Cravanzola, Valentina Brunella, Alessandro Damin and Domenica Scarano, after having first reported the preparation of polymer waste-derived microporous carbon microspheres (SBET ~800 m2/g) 100–300 μm in size, investigate the morphology, porous texture and the surface properties of carbon and of magnetic carbon microspheres by multiple techniques.*

The multi-technique methodology they used aims at an extensive description of the different characteristics of activated carbons with magnetic properties.

For the Atomic Force Microscopy described in this paper NANOSENSORS™ SSS-MFMR AFM probes for high resolution magnetic force imaging were used for the topography images as well as the MFM imaging.

Figure 7 from “From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies” by F. Cesano et al:
Three images described from left to right of Fe3O4-based carbon microspheres: first image on the left (a) AFM topography, middle image (b) the related phase signal, and the image on the right (c) MFM phase shift images at H = 60 nm lift height obtained in a second scan. The phase shift range in (c) is ~ 0.6 m°.
Figure 7 from “From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies” by F. Cesano et al:
Fe3O4-based carbon microspheres: (a) AFM topography, (b) the related phase signal, and (c) MFM phase shift images at H = 60 nm lift height obtained in a second scan. The phase shift range in (c) is ~ 0.6 m°. e description

*Federico Cesano, Sara Cravanzola, Valentina Brunella, Alessandro Damin and Domenica Scarano
From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies
Frontiers in Materials 6:84 (2019)
DOI: https://doi.org/10.3389/fmats.2019.00084

Please follow this external link to read the full research article: https://www.frontiersin.org/articles/10.3389/fmats.2019.00084/full

Open Access: The article « From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies” by Federico Cesano, Sara Cravanzola, Valentina Brunella, Alessandro Damin and Domenica Scarano which is cited above 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/.