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Slimani Y, Hannachi E, Koblischka-Veneva A, Koblischka MR. Excess Conductivity Analysis of an YBCO Foam Strut and Its Microstructure. Materials (Basel) 2024; 17:1649. [PMID: 38612161 PMCID: PMC11013011 DOI: 10.3390/ma17071649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 03/01/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024]
Abstract
Struts of a superconducting YBa2Cu3Oy (YBCO) foam prepared by the infiltration growth method on the base of commercial polyurethane foams were extracted from the bulk, and thoroughly characterized concerning the microstructure and the magnetoresistance, measured by the four-point technique. Optical microscopy, electron microscopy, electron backscatter diffraction and atomic force microscopy observations indicate a unique microstructure of the foam struts which shows a large amount of tiny Y2BaCuO5 (Y-211) particles (with diameters between 50 and 100 nm) being enclosed in channel-like grain boundaries between the YBCO grains and a one-of-a-kind surface of the struts covered with Ba3Cu5Oy-particles. The resistance data obtained at temperatures in the range 4.2 K ≤T≤ 150 K (applied magnetic fields ranging from 0 to 7 T) were analyzed in the framework of the fluctuation-induced conductivity (FIC) approach using the models of Aslamazov-Larkin (AL) and Lawrence-Doniach (LD). The resulting FIC curves reveal the presence of five distinct fluctuation regimes, namely, the short-wave (SWF), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and critical (CR) fluctuation domains. The analysis of the FIC data enable the coherence length in the direction of the c-axis at zero-temperature (ξc(0)), the irreversibility field (Birr), the upper critical magnetic field (Bc2), the critical current density at T= 0 K (Jc(0)) and several other parameters describing the the material's superconducting properties to be determined. The present data reveal that the minuscule Y-211 particles found along the YBCO grain boundaries alter the excess conductivity and the fluctuation behavior as compared to conventional YBCO samples, leading to a quite high value for Jc(0) for a sample with a non-optimized pinning landscape.
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Affiliation(s)
- Yassine Slimani
- Department of Biophysics, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia
| | - Essia Hannachi
- Faculty of Sciences of Bizerte, University of Carthage, Zarzouna 7021, Tunisia
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2
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Koblischka MR, Koblischka-Veneva A, Nouailhetas Q, Hajiri G, Berger K, Douine B, Gokhfeld D. Microstructural Parameters for Modelling of Superconducting Foams. Materials 2022; 15:ma15062303. [PMID: 35329755 PMCID: PMC8951565 DOI: 10.3390/ma15062303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 01/27/2023]
Abstract
Superconducting YBa2Cu3Oy (YBCO) foams were prepared using commercial open-cell, polyurethane foams as starting material to form ceramic Y2BaCuO5 foams which are then converted into superconducting YBCO by using the infiltration growth process. For modelling the superconducting and mechanical properties of the foam samples, a Kelvin-type cell may be employed as a first approach as reported in the literature for pure polyurethane foams. The results of a first modelling attempt in this direction are presented concerning an estimation of the possible trapped fields (TFs) and are compared to experimental results at 77 K. This simple modelling revealed already useful information concerning the best suited foam structure to realize large TF values, but it also became obvious that for various other parameters like magnetostriction, mechanical strength, percolative current flow and the details of the TF distribution, a refined model of a superconducting foam sample incorporating the real sample structure must be considered. Thus, a proper description of the specific microstructure of the superconducting YBCO foams is required. To obtain a set of reliable data, YBCO foam samples were investigated using optical microscopy, scanning electron microscopy and electron backscatter diffraction (EBSD). A variety of parameters including the size and shape of the cells and windows, the length and shape of the foam struts or ligaments and the respective intersection angles were determined to better describe the real foam structure. The investigation of the foam microstructures revealed not only the differences to the original polymer foams used as base material, but also provided further insights to the infiltration growth process via the large amount of internal surface in a foam sample.
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Affiliation(s)
- Michael Rudolf Koblischka
- Experimental Physics, Saarland University, P.O. Box 151150, D-66041 Saarbrücken, Germany; (A.K.-V.); (Q.N.)
- Correspondence:
| | - Anjela Koblischka-Veneva
- Experimental Physics, Saarland University, P.O. Box 151150, D-66041 Saarbrücken, Germany; (A.K.-V.); (Q.N.)
| | - Quentin Nouailhetas
- Experimental Physics, Saarland University, P.O. Box 151150, D-66041 Saarbrücken, Germany; (A.K.-V.); (Q.N.)
- GREEN, Université de Lorraine, F-54000 Nancy, France; (G.H.); (K.B.); (B.D.)
| | - Ghazi Hajiri
- GREEN, Université de Lorraine, F-54000 Nancy, France; (G.H.); (K.B.); (B.D.)
| | - Kévin Berger
- GREEN, Université de Lorraine, F-54000 Nancy, France; (G.H.); (K.B.); (B.D.)
| | - Bruno Douine
- GREEN, Université de Lorraine, F-54000 Nancy, France; (G.H.); (K.B.); (B.D.)
| | - Denis Gokhfeld
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia;
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Koblischka-Veneva A, Koblischka MR. ( RE)Ba 2Cu 3O 7-δ and the Roeser-Huber Formula. Materials (Basel) 2021; 14:ma14206068. [PMID: 34683658 PMCID: PMC8537038 DOI: 10.3390/ma14206068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/09/2021] [Accepted: 10/10/2021] [Indexed: 11/17/2022]
Abstract
We apply the Roeser–Huber formula to the (RE)Ba2Cu3O7−δ (REBCO with RE= rare earths) high-Tc superconducting material class to calculate the superconducting transition temperature, Tc, using the electronic configuration and the crystallographic data. In a former publication (H. P. Roeser et al., Acta Astronautica 2008, 62, 733–736), the basic idea was described and Tc was successfully calculated for the YBa2Cu3O7−δ compound with two oxygen doping levels δ= 0.04 and 0.45, but several open questions remained. One of the problems remaining was the determination of Tc for the δ= 0.45 sample, which can be explained regarding the various oxygen arrangements being possible within the copper-oxide plane. Having established this proper relation and using the various crystallographic data on the REBCO system available in the literature, we show that the Roeser–Huber equation is capable to calculate the Tc of the various REBCO compounds and the effects of strain and pressure on Tc, when preparing thin film samples. Furthermore, the characteristic length, x, determined for the REBCO systems sheds light on the size of the δTc-pinning sites being responsible for additional flux pinning and the peak effect.
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Affiliation(s)
- Anjela Koblischka-Veneva
- Experimental Physics, Saarland University, P.O. Box 151150, D-66041 Saarbrücken, Germany;
- Shibaura Research Laboratories, Shibaura Institute of Technology, 1-3-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan
| | - Michael Rudolf Koblischka
- Experimental Physics, Saarland University, P.O. Box 151150, D-66041 Saarbrücken, Germany;
- Shibaura Research Laboratories, Shibaura Institute of Technology, 1-3-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan
- Correspondence: or
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Dorget R, Nouailhetas Q, Colle A, Berger K, Sudo K, Ayat S, Lévêque J, Koblischka MR, Sakai N, Oka T, Douine B. Review on the Use of Superconducting Bulks for Magnetic Screening in Electrical Machines for Aircraft Applications. Materials (Basel) 2021; 14:ma14112847. [PMID: 34073417 PMCID: PMC8199450 DOI: 10.3390/ma14112847] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/20/2021] [Accepted: 05/23/2021] [Indexed: 11/16/2022]
Abstract
High-Temperature Superconductors (HTS) considerably accelerate the development of superconducting machines for electrical engineering applications such as fully electrical aircraft. This present contribution is an overview of different superconducting materials that can be used as magnetic screens for the inductor of high specific power electrical machines. The impact of the material properties, such as the critical temperature (Tc) and the critical current density (Jc), on the machine performances is evaluated. In addition, the relevance to flux modulation machines of different HTS bulk synthesis methods are addressed.
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Affiliation(s)
- Rémi Dorget
- Groupe de Recherche en Energie Electrique de Nancy, Université de Lorraine, GREEN, 54000 Nancy, France; (R.D.); (K.B.); (J.L.); (B.D.)
- Safran Tech, Electrical & Electronic Systems Research Group, Rue des Jeunes Bois, Châteaufort, 78114 Magny-Les-Hameaux, France;
| | - Quentin Nouailhetas
- Groupe de Recherche en Energie Electrique de Nancy, Université de Lorraine, GREEN, 54000 Nancy, France; (R.D.); (K.B.); (J.L.); (B.D.)
- Experimentalphysik, Saarland University, P.O. Box 151150, 66041 Saarbrücken, Germany;
- Correspondence:
| | | | - Kévin Berger
- Groupe de Recherche en Energie Electrique de Nancy, Université de Lorraine, GREEN, 54000 Nancy, France; (R.D.); (K.B.); (J.L.); (B.D.)
| | - Kimiaki Sudo
- Shibaura Institute of Technology, Tokyo 135-8548, Japan; (K.S.); (N.S.); (T.O.)
| | - Sabrina Ayat
- Safran Tech, Electrical & Electronic Systems Research Group, Rue des Jeunes Bois, Châteaufort, 78114 Magny-Les-Hameaux, France;
| | - Jean Lévêque
- Groupe de Recherche en Energie Electrique de Nancy, Université de Lorraine, GREEN, 54000 Nancy, France; (R.D.); (K.B.); (J.L.); (B.D.)
| | - Michael Rudolf Koblischka
- Experimentalphysik, Saarland University, P.O. Box 151150, 66041 Saarbrücken, Germany;
- Shibaura Institute of Technology, Tokyo 135-8548, Japan; (K.S.); (N.S.); (T.O.)
| | - Naomichi Sakai
- Shibaura Institute of Technology, Tokyo 135-8548, Japan; (K.S.); (N.S.); (T.O.)
| | - Tetsuo Oka
- Shibaura Institute of Technology, Tokyo 135-8548, Japan; (K.S.); (N.S.); (T.O.)
| | - Bruno Douine
- Groupe de Recherche en Energie Electrique de Nancy, Université de Lorraine, GREEN, 54000 Nancy, France; (R.D.); (K.B.); (J.L.); (B.D.)
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Koblischka MR, Slimani Y, Koblischka-Veneva A, Karwoth T, Zeng X, Hannachi E, Murakami M. Excess Conductivity Analysis of Polycrystalline FeSe Samples with the Addition of Ag. Materials (Basel) 2020; 13:ma13215018. [PMID: 33172199 PMCID: PMC7664390 DOI: 10.3390/ma13215018] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/31/2020] [Accepted: 11/03/2020] [Indexed: 11/20/2022]
Abstract
Bulk FeSe superconductors of the iron-based (IBS) “11” family containing various additions of silver were thoroughly investigated concerning the microstructure using optical microscopy and electron microscopy (TEM and SEM). The measurements of electrical resistivity were performed through the four-point technique in the temperature interval T= 2–150 K. The Aslamazov–Larkin model was employed to analyze the fluctuation-induced conductivity (FIC) in all acquired measurements. In all studied products, we found that the FIC curves consist of five different regimes of fluctuation, viz. critical region (CR), three-dimensional (3D), two-dimensional (2D), one-dimensional (1D), and shortwave fluctuation (SWF) regimes. The critical current density (Jc), the lower and upper critical magnetic fields (Bc1 and Bc2), the coherence length along the c-axis at zero-temperature (ξc(0)), and further parameters were assessed with regards to the silver amount within the products. The analyses discloses a diminution in the resistivity and a great reduction in ξc(0) with Ag addition. The optimal silver doping amount is achieved for 7 wt.%, which yields the best superconducting transition and the greatest Jc value.
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Affiliation(s)
- Michael Rudolf Koblischka
- Experimental Physics, Saarland University, P.O. Box 151150, D-66044 Saarbrücken, Germany; (A.K.-V.); (T.K.); (X.Z.)
- SIT Research Laboratories, Shibaura Institute of Technology, Tokyo 135-8548, Japan;
- Correspondence: or
| | - Yassine Slimani
- Department of Biophysics, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia;
| | - Anjela Koblischka-Veneva
- Experimental Physics, Saarland University, P.O. Box 151150, D-66044 Saarbrücken, Germany; (A.K.-V.); (T.K.); (X.Z.)
- SIT Research Laboratories, Shibaura Institute of Technology, Tokyo 135-8548, Japan;
| | - Thomas Karwoth
- Experimental Physics, Saarland University, P.O. Box 151150, D-66044 Saarbrücken, Germany; (A.K.-V.); (T.K.); (X.Z.)
| | - XianLin Zeng
- Experimental Physics, Saarland University, P.O. Box 151150, D-66044 Saarbrücken, Germany; (A.K.-V.); (T.K.); (X.Z.)
| | - Essia Hannachi
- Laboratory of Physics of Materials—Structures and Properties, Department of Physics, Faculty of Sciences of Bizerte, University of Carthage, Zarzouna 7021, Tunisia;
| | - Masato Murakami
- SIT Research Laboratories, Shibaura Institute of Technology, Tokyo 135-8548, Japan;
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Pavan Kumar
Naik S, Miryala M, Koblischka MR, Koblischka-Veneva A, Oka T, Murakami M. Production of Sharp-Edged and Surface-Damaged Y 2BaCuO 5 by Ultrasound: Significant Improvement of Superconducting Performance of Infiltration Growth-Processed YBa 2Cu 3O 7-δ Bulk Superconductors. ACS Omega 2020; 5:6250-6259. [PMID: 32258859 PMCID: PMC7114162 DOI: 10.1021/acsomega.9b02816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 02/13/2020] [Indexed: 06/11/2023]
Abstract
Growth and physical properties of bulk REBa2Cu3O7-δ (REBCO) superconductors fabricated by the infiltration growth (IG) method strongly depend on the initial size and morphology of the RE2BaCuO5 (211) particles. The present work details the novel method we developed for producing sharp-edged and surface-damaged 211 particles to be added to the REBCO bulks. We employed high-energy ultrasonic irradiation for pretreating the 211 particles and fabricated high-performance bulk single-grain YBa2Cu3O7-δ (YBCO) superconductors via the top-seeded IG process. Increasing the ultrasound irradiation power and time duration mechanically damaged the surface of the 211 particles, producing more fine and sharp edges. Systematic investigations of the microstructural properties of the final YBCO bulks indicated that the size and content of the 211 particles gradually decreased without any additional chemical doping. The effective grain refinement and improved interfacial defect densities enhanced the critical current density by a factor of two at 77 K and self-field as compared to a YBCO sample fabricated without any pretreatment. A maximum trapped field of 0.48 T at 77 K was obtained for a sample (20 mm diameter) with 211 particles treated for 60 min and 300 W ultrasound radiation. The effectiveness of the novel method is demonstrated by the superior performance of the YBCO bulk samples prepared as compared to bulk samples fabricated with the addition of Pt and CeO2. This method is novel, cost effective, and very convenient, maintaining high sample homogeneity, and is free of chemical contaminants as compared to other methods which significantly affect the properties of all REBCO bulk products grown by sintering, melt growth, and IG methods.
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Affiliation(s)
- Sugali Pavan Kumar
Naik
- Superconducting
Materials Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5, Toyosu,
Koto-ku, Tokyo 135-8548, Japan
- Electronics
and Photonics Research Institute, National
Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Central 2, Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Muralidhar Miryala
- Superconducting
Materials Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5, Toyosu,
Koto-ku, Tokyo 135-8548, Japan
| | - Michael Rudolf Koblischka
- Superconducting
Materials Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5, Toyosu,
Koto-ku, Tokyo 135-8548, Japan
| | - Anjela Koblischka-Veneva
- Superconducting
Materials Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5, Toyosu,
Koto-ku, Tokyo 135-8548, Japan
| | - Tetsuo Oka
- Superconducting
Materials Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5, Toyosu,
Koto-ku, Tokyo 135-8548, Japan
| | - Masato Murakami
- Superconducting
Materials Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5, Toyosu,
Koto-ku, Tokyo 135-8548, Japan
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7
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Koblischka-Veneva A, Koblischka MR, Schmauch J, Noudem J, Murakami M. Analysis of the microstructure of bulk MgB 2 using TEM, EBSD and t-EBSD. J Microsc 2019; 274:123-131. [PMID: 30852839 DOI: 10.1111/jmi.12790] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/03/2019] [Accepted: 03/07/2019] [Indexed: 01/20/2023]
Abstract
EBSD analysis can provide information about grain orientation, texture and grain boundary misorientation of bulk superconducting MgB2 samples intended for supermagnet applications. However, as the grain size of the MgB2 bulks is preferably in the 100-200 nm range, the common EBSD technique operating in reflection mode works only properly on highly dense samples. In order to achieve reasonably good Kikuchi pattern quality on all types of MgB2 samples, we apply here the newly developed transmission EBSD (t-EBSD) technique to spark-plasma sintered MgB2 samples. This method requires the preparation of TEM slices by means of focused ion-beam milling, which are then analysed within the SEM, operating with a custom-built sample holder. To obtain multiphase scans, we identified the Kikuchi pattern of the MgB4 phase which appears at higher reaction temperatures and may act as additional flux pinning sites. We present here for the first time EBSD mappings of multiple phases, which include MgB2 , MgB4 and MgO. LAY DESCRIPTION: The electron backscatter diffraction (EBSD) technique operating in the scanning electron microscope provides information on the crystallographic orientation the material by recording Kikuchi patterns. In polycrystalline samples, it becomes possible to analyse the orientations of the grains to each other. The metallic superconductor with the currently highest superconducting transition temperature, MgB2 with a Tc of 38.5 K, can be used in applications in polycrystalline form. One such application of interest are trapped field magnets or supermagnets, where the superconductor cooled in an applied magnetic field can trap the magnetic field as vortices at numerous flux pinning sites in the sample. When the external magnetic field is removed, the sample will stay magnetised as long as it is kept cool, and importantly, the trapped magnetic fields can be much higher as for any permanent magnet. However, the small size of the MgB2 grains in the 100-200 nanometre range requires a different approach when using the EBSD technique on such samples. The recently developed EBSD technique working in transmission mode (t-EBSD) helps considerably to image such materials. In this approach, a tiny TEM slice has to be milled out from the original sample by using focused ion beam milling. To understand the properties of the flux pinning in the spark-plasma sintered MgB2 sample, we had to identify the Kikuchi pattern of MgB4 , which is another, non-superconducting phase appearing at higher reaction temperatures required to compact the material. Using this information, we could perform EBSD scans using three different phases, MgB2 , MgB4 and MgO. The EBSD mappings enable to see where the secondary phase particles are located in the sample, and to judge if the particles could work as flux pinning sites.
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Affiliation(s)
- A Koblischka-Veneva
- Experimental Physics, Saarland University, Saarbrücken, Germany.,Superconducting Materials Laboratory, Department of Materials Science and Engineering, Shibaura Institute of Technology 3-7-5 Toyosu, Koto-ku, Tokyo, Japan
| | - M R Koblischka
- Experimental Physics, Saarland University, Saarbrücken, Germany.,Superconducting Materials Laboratory, Department of Materials Science and Engineering, Shibaura Institute of Technology 3-7-5 Toyosu, Koto-ku, Tokyo, Japan
| | - J Schmauch
- Experimental Physics, Saarland University, Saarbrücken, Germany
| | | | - M Murakami
- Superconducting Materials Laboratory, Department of Materials Science and Engineering, Shibaura Institute of Technology 3-7-5 Toyosu, Koto-ku, Tokyo, Japan
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Chen Y, Fitchorov T, Gao J, Koblischka-Veneva A, Koblischka MR, Vittoria C, Harris VG. Topochemical growth of textured polycrystalline barium hexaferrite from oriented antiferromagnetic alpha-FeOOH nanorods. Nanotechnology 2009; 20:445606. [PMID: 19809120 DOI: 10.1088/0957-4484/20/44/445606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nanorods of goethite, i.e. alpha-FeOOH, were mixed with BaCO3, dispersed in a polymer solution, and oriented under a 90 kOe magnetic field during polymerization. The orientation arose principally from the interaction of the magnetic field with the anisotropic antiferromagnetism of the goethite particles. The oriented antiferromagnetic particles act as seeds for the topochemical growth of BaFe12O19 ferrite grains along the [0001] direction. The degree of grain orientation was determined using magnetic measurements and orientation distribution functions and pole figures determined by electron backscatter diffraction analysis.
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Affiliation(s)
- Yajie Chen
- Department of Electrical and Computer Engineering, and the Center for Microwave Magnetic Materials and Integrated Circuits, Northeastern University, Boston, MA 02115, USA.
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9
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Koblischka MR, Wei JD, Richter C, Sulzbach TH, Hartmann U. Advanced cantilevers for magnetic force microscopy and high frequency magnetic force microscopy. Scanning 2008; 30:27-34. [PMID: 18302217 DOI: 10.1002/sca.20090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In order to improve the spatial resolution achieved by magnetic force microscopy (MFM) technique and its derivatives, we employ here advanced MFM tips fabricated by means of focused ion beam (FIB) milling. The magnetic coating applied on these tips is a CoCr film of 10 nm thickness. The MFM measurements on hard disk test samples reveal the achieved high resolution, and the measurement on a garnet film demonstrates the low invasiveness. High-frequency MFM (HF-MFM) is a development of the MFM technique to observe the HF stray fields emerging from magnetic recording writer poles at their operating conditions. By means of HF-MFM, magnetic recording writer poles are characterized in the frequency range 100-1,000 MHz. Up to now, all HF-MFM experiments conducted were using standard MFM cantilevers. From the HF-MFM images obtained using the advanced MFM cantilevers, it is clearly seen that the spatial resolution is considerably improved over the images obtained using standard MFM tips. However, the 10 nm thick magnetic coating of the cantilevers is found to work properly only at frequencies of up to about 500 MHz.
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Affiliation(s)
- M R Koblischka
- Institute of Experimental Physics, Saarland University, Saarbrücken, Germany.
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10
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Abstract
During the past ten years magnetic force microscopy (MFM) has become probably the most powerful general-purpose method for magnetic imaging. MFM can be applied under various environmental conditions and requires only little sample preparation. Basic research on magnetic materials as well as the mentioned industrial applications create an increasing demand for high-resolution magnetic imaging methods. This contribution will review some new concepts which have been realized in the field of advanced probe preparation, based on electron beam methods in order to improve the spatial resolution beyond 100nm. It is shown that the advanced probes allow high-resolution imaging of magnetic fine structures within thin film permalloy elements exhibiting a complicated cooperative magnetization reversal process. These investigations are of importance for various concepts underlying modern magnetic data storage developments. Furthermore, we present some developments of MFM to suit the needs of the magnetic recording industry.
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Affiliation(s)
- M R Koblischka
- Institute of Experimental Physics, University of Saarbrücken, P.O. Box 151150, D-66041, Saarbrücken, Germany.
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11
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Koblischka MR, Higuchi T, Sawada K, Yoo SI, Murakami M. Observation of multiple peaks in the magnetization curves of NdBa2Cu3O7 single crystals. Phys Rev B Condens Matter 1996; 54:R6893-R6896. [PMID: 9984407 DOI: 10.1103/physrevb.54.r6893] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Schuster T, Kuhn H, Brandt EH, Indenbom M, Koblischka MR, Konczykowski M. Flux motion in thin superconductors with inhomogeneous pinning. Phys Rev B Condens Matter 1994; 50:16684-16707. [PMID: 9976057 DOI: 10.1103/physrevb.50.16684] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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13
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Schuster T, Indenbom MV, Koblischka MR, Kuhn H, Kronmüller H. Observation of current-discontinuity lines in type-II superconductors. Phys Rev B Condens Matter 1994; 49:3443-3452. [PMID: 10011207 DOI: 10.1103/physrevb.49.3443] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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14
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Schuster T, Kuhn H, Koblischka MR, Theuss H, Kronmüller H, Leghissa M, Kraus M, Saemann-Ischenko G. Enhancement of critical current densities by heavy-ion irradiation in YBa2Cu3O7- delta observed using the high-resolution Faraday effect. Phys Rev B Condens Matter 1993; 47:373-383. [PMID: 10004454 DOI: 10.1103/physrevb.47.373] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Schuster T, Koblischka MR, Kuhn H, Kronmüller H, Leghissa M, Gerhäuser W, Saemann-Ischenko G, Neumüller HW, Klaumünzer S. Observation of flux penetration in Bi2Sr2CaCu2O8+ delta crystals with irradiation-induced columnar defects. Phys Rev B Condens Matter 1992; 46:8496-8504. [PMID: 10002614 DOI: 10.1103/physrevb.46.8496] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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