Pub Date : 2005-04-04DOI: 10.1109/INTMAG.2005.1463521
B. Rellinghaus, O. Dmitrieva, M. Liedke, J. Fassbender
In the present study, post-deposition 5 keV He irradiation has been performed on such gas phase prepared FePt nanoparticles. Structural characterization of the samples is carried out by means of high resolution transmission electron microscopy (HRTEM). The power spectra obtained by Fourier transform of the original images clearly show that the particles are multiply twinned and of icosahedral structure but after irradiation, the particles are now of single crystal fcc structure and their mean diameter is reduced. This size reduction is ascribed to irradiation induced sputtering of the particles.
{"title":"Structural phase transformation of FePt nanoparticles by ion irradiation","authors":"B. Rellinghaus, O. Dmitrieva, M. Liedke, J. Fassbender","doi":"10.1109/INTMAG.2005.1463521","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463521","url":null,"abstract":"In the present study, post-deposition 5 keV He irradiation has been performed on such gas phase prepared FePt nanoparticles. Structural characterization of the samples is carried out by means of high resolution transmission electron microscopy (HRTEM). The power spectra obtained by Fourier transform of the original images clearly show that the particles are multiply twinned and of icosahedral structure but after irradiation, the particles are now of single crystal fcc structure and their mean diameter is reduced. This size reduction is ascribed to irradiation induced sputtering of the particles.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"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":"114436325","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.2005.1464240
P. Kovintavewat, J. Barry, M. Fatih Erden, E. Kurtas
Per-survivor iterative timing recovery was proposed to jointly perform timing recovery, equalization, and error-correction decoding. In this paper the robustness of per-survivor iterative timing recovery against thermal asperity (TA) and in ultra-high media noise environment in perpendicular recording channels was investigated.
{"title":"Robustness of per-survivor iterative timing recovery in perpendicular recording channels","authors":"P. Kovintavewat, J. Barry, M. Fatih Erden, E. Kurtas","doi":"10.1109/INTMAG.2005.1464240","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464240","url":null,"abstract":"Per-survivor iterative timing recovery was proposed to jointly perform timing recovery, equalization, and error-correction decoding. In this paper the robustness of per-survivor iterative timing recovery against thermal asperity (TA) and in ultra-high media noise environment in perpendicular recording channels was investigated.","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":"122036236","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.2005.1464018
M. Phan, Seong-cho Yu, N. D. Tho, N. Chau
The discovery of large low-field magnetocaloric effects (MCE) in polycrystalline Pr/sub 1-x/Pb/sub x/MnO/sub 3/ (0.1 /spl les/ x /spl les/ 0.5) is reported, which were prepared by the conventional ceramic technique. Upon 13.5 kOe applied field, the magnetic entropy change (/spl Delta/S/sub M/) reaches values of 3.91, 3.68 and 3.34 J/kg K for x = 0.1, 0.4 and 0.5 compositions, respectively, and which are larger than that of the well-known magnetic refrigerant material of Gd, /spl Delta/S/sub M/ = 3.32 J/kg K. These new perovskites having large /spl Delta/S/sub M/ caused by a low applied magnetic field that can be generated by permanent magnets are excellent candidates, for working materials in magnetic refrigeration in a temperature range of 150 - 270 K. Furthermore, the peak of /spl Delta/S/sub M/ locates at a temperature that is higher than its Curie temperature and it is considerably shifted to a higher value when the magnetic field is increased. This observation opens a new window to explore the magnetic refrigeration in a high temperature regime.
{"title":"Low-field magnetocaloric effect in Pr/sub 1-x/Pb/sub x/MnO/sub 3/ (0.1 /spl les/ x /spl les/ 0.5) perovskites","authors":"M. Phan, Seong-cho Yu, N. D. Tho, N. Chau","doi":"10.1109/INTMAG.2005.1464018","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464018","url":null,"abstract":"The discovery of large low-field magnetocaloric effects (MCE) in polycrystalline Pr/sub 1-x/Pb/sub x/MnO/sub 3/ (0.1 /spl les/ x /spl les/ 0.5) is reported, which were prepared by the conventional ceramic technique. Upon 13.5 kOe applied field, the magnetic entropy change (/spl Delta/S/sub M/) reaches values of 3.91, 3.68 and 3.34 J/kg K for x = 0.1, 0.4 and 0.5 compositions, respectively, and which are larger than that of the well-known magnetic refrigerant material of Gd, /spl Delta/S/sub M/ = 3.32 J/kg K. These new perovskites having large /spl Delta/S/sub M/ caused by a low applied magnetic field that can be generated by permanent magnets are excellent candidates, for working materials in magnetic refrigeration in a temperature range of 150 - 270 K. Furthermore, the peak of /spl Delta/S/sub M/ locates at a temperature that is higher than its Curie temperature and it is considerably shifted to a higher value when the magnetic field is increased. This observation opens a new window to explore the magnetic refrigeration in a high temperature regime.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"7 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":"122134618","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.2005.1464098
Hwan-Soo Lee, J. Bain, Sooyoul Hong, H.J. Lee
A perpendicular medium with a soft underlayer (SUL) combined with a single-pole head (SPH) is the most common implementation of perpendicular recording. This paper discusses the influence of media background on the write/read performance for both media's. The introduction of an antiferromagnetic (AFM) layer underneath SUL is also reported to help avoid additional media noise due to the domain wall instabilities of the SUL. However, such AFM layer can increase stray fields arising from the recording layer giving rise to notable effect on recording performance.
{"title":"Influence of media background on write/read performance in perpendicular media with an antiferromagnetic layer","authors":"Hwan-Soo Lee, J. Bain, Sooyoul Hong, H.J. Lee","doi":"10.1109/INTMAG.2005.1464098","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464098","url":null,"abstract":"A perpendicular medium with a soft underlayer (SUL) combined with a single-pole head (SPH) is the most common implementation of perpendicular recording. This paper discusses the influence of media background on the write/read performance for both media's. The introduction of an antiferromagnetic (AFM) layer underneath SUL is also reported to help avoid additional media noise due to the domain wall instabilities of the SUL. However, such AFM layer can increase stray fields arising from the recording layer giving rise to notable effect on recording performance.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"33 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":"129597308","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.2005.1464341
H. Bayani, I. Sasada
A theoretical model for eddy current non-destructive testing was developed. In this model, eddy current distribution in the aluminum plate was calculated using the equations developed by Dodd and Deeds. The magnetic field caused by the interaction of flaw and eddy currents was also evaluated. The validity of this model has been confirmed by experimental results.
{"title":"A model for quantitative evaluation of the magnetic field caused by eddy current interaction with a flaw in conductor plates","authors":"H. Bayani, I. Sasada","doi":"10.1109/INTMAG.2005.1464341","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464341","url":null,"abstract":"A theoretical model for eddy current non-destructive testing was developed. In this model, eddy current distribution in the aluminum plate was calculated using the equations developed by Dodd and Deeds. The magnetic field caused by the interaction of flaw and eddy currents was also evaluated. The validity of this model has been confirmed by experimental results.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"30 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":"128762697","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.2005.1464430
K. Tsumekawa, D. Djayaprawira, M. Nagai, H. Maehara, S. Yamagata, N. Watanabe
The effect of capping layer (CL) material on tunnel magnetoresistance (TMR) and magnetic properties in CoFeB/MgO/CoFeB magnetic tunnel junctions has been studied. The use of CL materials such as Ta, Ru, PtMn, Mg and IrMn yielded high MR ratio of more than 100%. The use of ferromagnetic materials, on the other hand, such as NiFe, CoFe or Fe decreased the MR ratio, as well as using Al, Cu, NiFeCr or Ir. The dependence of coercivity on CL materials for the same samples are also studied. It was speculated from the results that the degradation of the TMR and the magnetic properties when particular capping layer materials were used, is due to the formation of a reactive layer between the free layer and the capping layer.
{"title":"Effect of capping layer material on tunnel magnetoresistance in CoFeB-MgO-CoFeB magnetic tunnel junctions","authors":"K. Tsumekawa, D. Djayaprawira, M. Nagai, H. Maehara, S. Yamagata, N. Watanabe","doi":"10.1109/INTMAG.2005.1464430","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464430","url":null,"abstract":"The effect of capping layer (CL) material on tunnel magnetoresistance (TMR) and magnetic properties in CoFeB/MgO/CoFeB magnetic tunnel junctions has been studied. The use of CL materials such as Ta, Ru, PtMn, Mg and IrMn yielded high MR ratio of more than 100%. The use of ferromagnetic materials, on the other hand, such as NiFe, CoFe or Fe decreased the MR ratio, as well as using Al, Cu, NiFeCr or Ir. The dependence of coercivity on CL materials for the same samples are also studied. It was speculated from the results that the degradation of the TMR and the magnetic properties when particular capping layer materials were used, is due to the formation of a reactive layer between the free layer and the capping layer.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"57 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":"128774656","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.2005.1463756
S. Jang, J. Seo, J.K. Kown, J. Choi, H. Cho
The permanent magnet linear synchronous motors (PMLSM) are proposed for many applications ranging from ground transportation to reciprocating servo system and conveyance system for their simple structure and high performance. Generally, the acceleration and deceleration experiment of PMLSM is very difficult because it has restricted limits of operating. Therefore, this paper proposes disk type PMLSM in order to solve problem stated above. Since the proposed disk type PMLSM has infinite operation limits, it can be solved a problem in acceleration and deceleration experiment of PMLSM. This paper also deals with the analysis of disk type PMLSM considering slot opening and skew effect for a various air-gap length, in terms of air-gap flux density and detent force.
{"title":"Experiment and characteristic analysis of disk type PMLSM with Halbach array","authors":"S. Jang, J. Seo, J.K. Kown, J. Choi, H. Cho","doi":"10.1109/INTMAG.2005.1463756","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463756","url":null,"abstract":"The permanent magnet linear synchronous motors (PMLSM) are proposed for many applications ranging from ground transportation to reciprocating servo system and conveyance system for their simple structure and high performance. Generally, the acceleration and deceleration experiment of PMLSM is very difficult because it has restricted limits of operating. Therefore, this paper proposes disk type PMLSM in order to solve problem stated above. Since the proposed disk type PMLSM has infinite operation limits, it can be solved a problem in acceleration and deceleration experiment of PMLSM. This paper also deals with the analysis of disk type PMLSM considering slot opening and skew effect for a various air-gap length, in terms of air-gap flux density and detent force.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"104 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":"124687908","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.2005.1464019
M. Ogita, T. Ito, M. Hafezzullah, H. Nonoyama, M. Isai, I. Mogi, S. Awaji, K. Yokoo
The Hall signals of Ga and Hg metals at liquid and solid states obtained through a new simultaneous method have been examined and compared with those of amorphous metals and solid state semiconductors of Si and InSb single crystals. Liquid metals of Hg and Ga of 5 N pure, para and ferromagnetic films of amorphous iron, and single crystals of Si and InSb were used as samples. Liquid metals were enclosed in the cell made of Macor or Pyrex glass, in which ditch is 200 and 400 /spl mu/m deep. The temperature was monitored and controlled within 0.5/spl deg/C by a thermocouple buried at the bottom of the cell. DC magnetic field of low field less than 0.3 Tesla is applied with a lab electromagnet, a superconductor magnet for high magnetic field up to 9 Tesla. Liquid metals such as Hg and Ga show the Hall effect and negligible magnetoresistance effect in the solid state, but the magnetoresistance effect in the liquid state appears much larger than in the solid state and badly affects the Hall effect.. It is also found that there is the magnetoresistance effect even in Si single crystal although the effect cannot normally be observed in low magnetic field less than 1 Tesla. For the ferromagnetic materials, the Hall signal is very much affected by the magnetoresistance.
{"title":"A new simultaneous method of Hall and magnetoresistance measurements at low and high magnetic field on liquid and amorphous metals, and semiconductors","authors":"M. Ogita, T. Ito, M. Hafezzullah, H. Nonoyama, M. Isai, I. Mogi, S. Awaji, K. Yokoo","doi":"10.1109/INTMAG.2005.1464019","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464019","url":null,"abstract":"The Hall signals of Ga and Hg metals at liquid and solid states obtained through a new simultaneous method have been examined and compared with those of amorphous metals and solid state semiconductors of Si and InSb single crystals. Liquid metals of Hg and Ga of 5 N pure, para and ferromagnetic films of amorphous iron, and single crystals of Si and InSb were used as samples. Liquid metals were enclosed in the cell made of Macor or Pyrex glass, in which ditch is 200 and 400 /spl mu/m deep. The temperature was monitored and controlled within 0.5/spl deg/C by a thermocouple buried at the bottom of the cell. DC magnetic field of low field less than 0.3 Tesla is applied with a lab electromagnet, a superconductor magnet for high magnetic field up to 9 Tesla. Liquid metals such as Hg and Ga show the Hall effect and negligible magnetoresistance effect in the solid state, but the magnetoresistance effect in the liquid state appears much larger than in the solid state and badly affects the Hall effect.. It is also found that there is the magnetoresistance effect even in Si single crystal although the effect cannot normally be observed in low magnetic field less than 1 Tesla. For the ferromagnetic materials, the Hall signal is very much affected by the magnetoresistance.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"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":"129422047","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.2005.1463434
K. Sekiguchi, E. Saitoh, H. Miyajima
The reduction of size in magnetic materials gives rise to new effects with great potential for spin-based applications. For example, the giant magnetoresistance (GMR) effect observed in nanometer-sized ferromagnetic contacts (nanocontact MR) is thought to be promising for future magnetoresistive sensors; the nanocontact MR is far larger than the normal GMR. Theoretically, it was predicted that the giant MR in nanocontact is the scattering of ballistic electrons. It is then an important issue to clarify the origin of the MR experimentally. In this work, we present detailed nanocontact MR in the conductance-quantization regime where the electron transport is definitely ballistic.
{"title":"The relation between nanocontact magnetoresistance and conductance quantized states","authors":"K. Sekiguchi, E. Saitoh, H. Miyajima","doi":"10.1109/INTMAG.2005.1463434","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1463434","url":null,"abstract":"The reduction of size in magnetic materials gives rise to new effects with great potential for spin-based applications. For example, the giant magnetoresistance (GMR) effect observed in nanometer-sized ferromagnetic contacts (nanocontact MR) is thought to be promising for future magnetoresistive sensors; the nanocontact MR is far larger than the normal GMR. Theoretically, it was predicted that the giant MR in nanocontact is the scattering of ballistic electrons. It is then an important issue to clarify the origin of the MR experimentally. In this work, we present detailed nanocontact MR in the conductance-quantization regime where the electron transport is definitely ballistic.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"44 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":"126708324","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.2005.1464493
H. Nishihara, K. Komiyama, I. Oguro, T. Kanomata, T. Harada
The experimental behaviors of magnetization process in pure nickel which has a moment of 0.6 /spl mu//sub B/ and a Curie temperature of about 600 K is investigated. Results confirmed that the theory, recently developed by Takahashi, on weakly itinerant-electron ferromagnets is applicable even to magnetically stronger case of itinerant ferromagnet. The amount of impurities and the effects of demagnetizing field were observed to have no effect on the result of the study.
{"title":"Magnetization process of nickel near the Curie temperature","authors":"H. Nishihara, K. Komiyama, I. Oguro, T. Kanomata, T. Harada","doi":"10.1109/INTMAG.2005.1464493","DOIUrl":"https://doi.org/10.1109/INTMAG.2005.1464493","url":null,"abstract":"The experimental behaviors of magnetization process in pure nickel which has a moment of 0.6 /spl mu//sub B/ and a Curie temperature of about 600 K is investigated. Results confirmed that the theory, recently developed by Takahashi, on weakly itinerant-electron ferromagnets is applicable even to magnetically stronger case of itinerant ferromagnet. The amount of impurities and the effects of demagnetizing field were observed to have no effect on the result of the study.","PeriodicalId":273174,"journal":{"name":"INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005.","volume":"20 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":"127037584","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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