Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464009
P. Park, V. Shifrin, Young Gyun Kirn, Mun-Seog Kim, Kyu-Tae Kim
A system for the Earth-magnetic-field (EMF) compensation has been developed, which is essential for the calibration of a precise magnetometers, sensors and for the material researches. In addition to the original function of the EMF compensation, the system can reproduce quite precise and stable magnetic field (MF) in the range of 20 /spl mu/T to 1.2 mT. The system, operated in a non-magnetic environment, consists of 3-axis Helmholtz coils, current stabilizer, precision solenoid, and temperature-control unit.
{"title":"Automatic compensation of Earth magnetic field and calibration system of magnetometers below 1 mT","authors":"P. Park, V. Shifrin, Young Gyun Kirn, Mun-Seog Kim, Kyu-Tae Kim","doi":"10.1109/INTMAG.2005.1464009","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464009","url":null,"abstract":"A system for the Earth-magnetic-field (EMF) compensation has been developed, which is essential for the calibration of a precise magnetometers, sensors and for the material researches. In addition to the original function of the EMF compensation, the system can reproduce quite precise and stable magnetic field (MF) in the range of 20 /spl mu/T to 1.2 mT. The system, operated in a non-magnetic environment, consists of 3-axis Helmholtz coils, current stabilizer, precision solenoid, and temperature-control unit.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"623 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113987288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464435
Sungjin Ahn, T. Kato, H. Kubota, Y. Ando, T. Miyazaki
Two kinds of MTJs were prepared using magnetron sputtering: a conventional polycrystalline MTJ with multilayer structure of Si(100)/SiO/sub 2//Ta 5 nm/NiFe 3 nm/Cu 20 nm/NiFe 3 nm/IrMn 10 nm/CoFe 40 nm/Al 1.6 nm-O/CoFe 4 nm/NiFe 20 nm/Ta 5 nm and a semi-epitaxial MTJ with a multilayer structures of Al/sub 2/O/sub 3/ (0001)/Pt (111) 20 nm/NiFe (111) 50 nm/Al 1.6 nm-O/CoFe 4 nm/IrMn 10 nm/NiFe 30 nm. The effect of the state of a ferromagnet/insulator interface on the bias-voltage dependence of TMR was investigated. It was found that the more crystal structure of bottom FM electrode improves, the more plasma oxidation proceeds uniformly and V/sub +1/2/ (bottom interface) increases. V/sub -1/2/ (top interface), on the other hand, are similar regardless of crystal structure of the bottom FM electrode.
{"title":"Bias-voltage dependence of tunnel magnetoresistance depending on the crystal structure of bottom ferromagnetic electrode","authors":"Sungjin Ahn, T. Kato, H. Kubota, Y. Ando, T. Miyazaki","doi":"10.1109/INTMAG.2005.1464435","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464435","url":null,"abstract":"Two kinds of MTJs were prepared using magnetron sputtering: a conventional polycrystalline MTJ with multilayer structure of Si(100)/SiO/sub 2//Ta 5 nm/NiFe 3 nm/Cu 20 nm/NiFe 3 nm/IrMn 10 nm/CoFe 40 nm/Al 1.6 nm-O/CoFe 4 nm/NiFe 20 nm/Ta 5 nm and a semi-epitaxial MTJ with a multilayer structures of Al/sub 2/O/sub 3/ (0001)/Pt (111) 20 nm/NiFe (111) 50 nm/Al 1.6 nm-O/CoFe 4 nm/IrMn 10 nm/NiFe 30 nm. The effect of the state of a ferromagnet/insulator interface on the bias-voltage dependence of TMR was investigated. It was found that the more crystal structure of bottom FM electrode improves, the more plasma oxidation proceeds uniformly and V/sub +1/2/ (bottom interface) increases. V/sub -1/2/ (top interface), on the other hand, are similar regardless of crystal structure of the bottom FM electrode.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114859978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463597
Y. Aoyama, K. Miyata, K. Ohashi
The eddy current loss of a Nd-Fe-B sintered magnet is estimated from temperature rise rate of their magnets. The obtained values of the eddy current loss coincide with the simulated data of the Integral Element Method. The method of dividing magnet is found effective in the suppression of the current loss. Also, it is observed that the higher harmonic effects on the alternating current are simple addition of each harmonics.
{"title":"Simulations and experiments on eddy current in Nd-Fe-B magnets","authors":"Y. Aoyama, K. Miyata, K. Ohashi","doi":"10.1109/INTMAG.2005.1463597","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463597","url":null,"abstract":"The eddy current loss of a Nd-Fe-B sintered magnet is estimated from temperature rise rate of their magnets. The obtained values of the eddy current loss coincide with the simulated data of the Integral Element Method. The method of dividing magnet is found effective in the suppression of the current loss. Also, it is observed that the higher harmonic effects on the alternating current are simple addition of each harmonics.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124386914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463858
N. Katayama, T. Maekawa, S. Yamamoto, Xiaoxi Liu, A. Morasiko, M. Matsumoto
In this experiment, Fe:Cu granular precursor is first deposited; FePt:Cu granular films are successfully prepared by interlayer diffusion of the first layer of Fe:Cu precursor and a second layer of Pt. This technique provided more degree of freedom on preparation of artificially granular films. The preparation, structure, and magnetic properties of the films have been investigated.
{"title":"Toward self assembly of L1/sub 0/-FePt nanoparticles by sputtering","authors":"N. Katayama, T. Maekawa, S. Yamamoto, Xiaoxi Liu, A. Morasiko, M. Matsumoto","doi":"10.1109/INTMAG.2005.1463858","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463858","url":null,"abstract":"In this experiment, Fe:Cu granular precursor is first deposited; FePt:Cu granular films are successfully prepared by interlayer diffusion of the first layer of Fe:Cu precursor and a second layer of Pt. This technique provided more degree of freedom on preparation of artificially granular films. The preparation, structure, and magnetic properties of the films have been investigated.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"56 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124507853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463690
A. Sandhu, H. Handa
There is intense worldwide activity in the development of instrumentation for medical diagnosis and bioscreening based on biological labeling and detection of superparamagnetic particles. This paper describes recent results of a systematic study on the fabrication of high sensitivity micro and nano-Hall devices for biomedical applications using a wide range of materials. Issues related to the ease of fabrication, scalability, magnetic field sensitivity and functionalization will be discussed. The extensive variety of materials available for Hall sensor fabrication offers a highly flexible, 'tailor-made' route for the development of instrumentation for detection and analysis of biological labeled superparamagnetic particles. The devices described in this paper (InSb linear arrays, InAs 'bridge-type' sensor, bismuth thin film nano-Hall sensor, GaN/AlGaN 2DEG sensor) were incorporated into the measurement system as described and successfully used to detect magnetic beads ranging between 0.12 to 2.8 microns in diameter. The electrical characteristics of novel micro-Hall sensors fabricated using GaN/AlGaN 2DEG heterostructures and InAs bridge structures are described. Methods for immobilization of DNA and other biomolecules onto the surfaces of these devices will also be discussed.
{"title":"Practical Hall effect sensors for biomedical instrumentation - 'horses for courses'","authors":"A. Sandhu, H. Handa","doi":"10.1109/INTMAG.2005.1463690","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463690","url":null,"abstract":"There is intense worldwide activity in the development of instrumentation for medical diagnosis and bioscreening based on biological labeling and detection of superparamagnetic particles. This paper describes recent results of a systematic study on the fabrication of high sensitivity micro and nano-Hall devices for biomedical applications using a wide range of materials. Issues related to the ease of fabrication, scalability, magnetic field sensitivity and functionalization will be discussed. The extensive variety of materials available for Hall sensor fabrication offers a highly flexible, 'tailor-made' route for the development of instrumentation for detection and analysis of biological labeled superparamagnetic particles. The devices described in this paper (InSb linear arrays, InAs 'bridge-type' sensor, bismuth thin film nano-Hall sensor, GaN/AlGaN 2DEG sensor) were incorporated into the measurement system as described and successfully used to detect magnetic beads ranging between 0.12 to 2.8 microns in diameter. The electrical characteristics of novel micro-Hall sensors fabricated using GaN/AlGaN 2DEG heterostructures and InAs bridge structures are described. Methods for immobilization of DNA and other biomolecules onto the surfaces of these devices will also be discussed.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124518441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464160
K. Suzuki, Y. Satoh, M. Itoh, M. Matsubara, A. Sawada
The CrO/sub 2/ films were deposited on ZrO/sub 2/ substrates using the ingot of Cr 83 at.% and Ru 17 at.% and oxidized flowing the pure oxygen gas. The X-ray diffraction, the magnetoresistance and temperature dependence of the resistance measurements, and the observation of the image of magnetic force microscope (MFM) show the films include the Ru doped CrO/sub 2/ with Curie temperature lager than that of pure CrO/sub 2/.
{"title":"Effects of impurity doping in CrO/sub 2/","authors":"K. Suzuki, Y. Satoh, M. Itoh, M. Matsubara, A. Sawada","doi":"10.1109/INTMAG.2005.1464160","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464160","url":null,"abstract":"The CrO/sub 2/ films were deposited on ZrO/sub 2/ substrates using the ingot of Cr 83 at.% and Ru 17 at.% and oxidized flowing the pure oxygen gas. The X-ray diffraction, the magnetoresistance and temperature dependence of the resistance measurements, and the observation of the image of magnetic force microscope (MFM) show the films include the Ru doped CrO/sub 2/ with Curie temperature lager than that of pure CrO/sub 2/.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126263245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463924
Jin Lu, M. F. Moura
High-rate low-density parity-check (LDPC) codes are the focus of intense research in magnetic recording because, when decoded by the iterative sum-product algorithm, they show decoding performance close to the Shannon capacity. LDPC codes can be described by a bipartite graph called Tanner graph. The length g of the shortest cycle in a Tanner graph is referred to as the girth g of the graph. Since large girth leads to more efficient decoding and large minimum distance, LDPC codes with large girth are particularly desired. We propose a class of structured LDPC codes with large girth and flexible code rates, called partition-and-shift LDPC codes (PS-LDPC).
{"title":"Partition-and-shift LDPC codes for high density magnetic recording","authors":"Jin Lu, M. F. Moura","doi":"10.1109/INTMAG.2005.1463924","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463924","url":null,"abstract":"High-rate low-density parity-check (LDPC) codes are the focus of intense research in magnetic recording because, when decoded by the iterative sum-product algorithm, they show decoding performance close to the Shannon capacity. LDPC codes can be described by a bipartite graph called Tanner graph. The length g of the shortest cycle in a Tanner graph is referred to as the girth g of the graph. Since large girth leads to more efficient decoding and large minimum distance, LDPC codes with large girth are particularly desired. We propose a class of structured LDPC codes with large girth and flexible code rates, called partition-and-shift LDPC codes (PS-LDPC).","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126287279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463931
E. Saitoh, M. Nozue, H. Miyajima, T. Yamaoka
Direct observation of the dynamics of a single domain wall (DW) in a NiFe-Cu nanowire is investigated. This reveals that such a topological particle indeed has a very small but finite mass of 6.6/spl times/10/sup -23/ kg, and interacts with high-frequency ac electric currents by exchanging momentum. This measurement is made possible by observing resonance of a single DW in which DW motion induced by a oscillating electric current in a tunable potential is used. The dominant mechanisms in these nanowires arise from the exchange coupling between the local magnetization and the spin of conduction electrons. The first mechanism is due to the reflection of conduction electrons by the DW, called momentum transfer. The other is the transfer of the spin angular momentum from conduction electrons to the DW as the electrons pass through the DW. This spin-transfer effect is proportional to the spin polarization of the current.
{"title":"Current induced oscillation of a single magnetic domain wall","authors":"E. Saitoh, M. Nozue, H. Miyajima, T. Yamaoka","doi":"10.1109/INTMAG.2005.1463931","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463931","url":null,"abstract":"Direct observation of the dynamics of a single domain wall (DW) in a NiFe-Cu nanowire is investigated. This reveals that such a topological particle indeed has a very small but finite mass of 6.6/spl times/10/sup -23/ kg, and interacts with high-frequency ac electric currents by exchanging momentum. This measurement is made possible by observing resonance of a single DW in which DW motion induced by a oscillating electric current in a tunable potential is used. The dominant mechanisms in these nanowires arise from the exchange coupling between the local magnetization and the spin of conduction electrons. The first mechanism is due to the reflection of conduction electrons by the DW, called momentum transfer. The other is the transfer of the spin angular momentum from conduction electrons to the DW as the electrons pass through the DW. This spin-transfer effect is proportional to the spin polarization of the current.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126350497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1464218
S. Parkin
Superconducting tunneling spectroscopy (STS) was used in this study to determine the spin polarization in tunnel junctions and spin injectors. STS showed that the polarization of the tunneling current from the 3d transition metal ferromagnets (FM) through amorphous aluminum oxide tunnel barriers is about 40 to 50% and is largely independent of the FM crystal structure and orientation. However, the same 3d transition metal ferromagnets and their alloys, when formed in the bcc crystal structure, and in conjunction with crystalline magnesium oxide tunnel barriers exhibit much higher tunneling spin polarization values of up to /spl sim/85%. Also, MgO based tunnel spin injectors for semiconductor spintronics was discussed.
{"title":"Giant tunneling magnetoresistance and spin polarization in tunnel junctions and spin injectors","authors":"S. Parkin","doi":"10.1109/INTMAG.2005.1464218","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464218","url":null,"abstract":"Superconducting tunneling spectroscopy (STS) was used in this study to determine the spin polarization in tunnel junctions and spin injectors. STS showed that the polarization of the tunneling current from the 3d transition metal ferromagnets (FM) through amorphous aluminum oxide tunnel barriers is about 40 to 50% and is largely independent of the FM crystal structure and orientation. However, the same 3d transition metal ferromagnets and their alloys, when formed in the bcc crystal structure, and in conjunction with crystalline magnesium oxide tunnel barriers exhibit much higher tunneling spin polarization values of up to /spl sim/85%. Also, MgO based tunnel spin injectors for semiconductor spintronics was discussed.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126468245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463616
I. Dumitri, F. Li, J. Wiley, D. Cimpoesu, A. Stancu, L. Spinu
The dipolar interaction fields in an electrochemically deposited Ni nanowires (samples labeled Ni2, Ni3, Ni6) are characterized using the ferromagnetic resonance. The major hysteresis loops (MHL) are measured using vibrating sample magnetometer with the applied field perpendicular and parallel to the membrane plane. It is observed that the MHL squareness, S ,for the in plane and perpendicular configurations is S/sub inplane/ < S/sub perp/ for Ni2, Ni3 and S/sub inplane/ > S/sub perp/ for Ni6. The observed differences in the MHL are related to the nanowires lengths which determine different magnetic interactions between nanowires.
{"title":"Study of magnetic interaction in metallic nanowires networks","authors":"I. Dumitri, F. Li, J. Wiley, D. Cimpoesu, A. Stancu, L. Spinu","doi":"10.1109/INTMAG.2005.1463616","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463616","url":null,"abstract":"The dipolar interaction fields in an electrochemically deposited Ni nanowires (samples labeled Ni2, Ni3, Ni6) are characterized using the ferromagnetic resonance. The major hysteresis loops (MHL) are measured using vibrating sample magnetometer with the applied field perpendicular and parallel to the membrane plane. It is observed that the MHL squareness, S ,for the in plane and perpendicular configurations is S/sub inplane/ < S/sub perp/ for Ni2, Ni3 and S/sub inplane/ > S/sub perp/ for Ni6. The observed differences in the MHL are related to the nanowires lengths which determine different magnetic interactions between nanowires.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126410809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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