Pub Date : 2014-11-06DOI: 10.1109/MSSC.2014.6947689
X. Chen, R. Ramanujan
Mn-Fe-P-Ge alloys are highly attractive magnetocaloric materials for near room temperature magnetic cooling applications. The structural and magnetic phase transition of a Mn1.1Fe0.9P0.74Ge0.26 alloy was investigated and an Arrott plot analysis conducted. It was found that this alloy exhibits ferromagnetism at room temperature and the magneto-structural transition responsible for the magnetocaloric effect was first order in nature.
{"title":"Structural and magnetic behavior of a Mn-Fe-P-Ge magnetocaloric alloy","authors":"X. Chen, R. Ramanujan","doi":"10.1109/MSSC.2014.6947689","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947689","url":null,"abstract":"Mn-Fe-P-Ge alloys are highly attractive magnetocaloric materials for near room temperature magnetic cooling applications. The structural and magnetic phase transition of a Mn1.1Fe0.9P0.74Ge0.26 alloy was investigated and an Arrott plot analysis conducted. It was found that this alloy exhibits ferromagnetism at room temperature and the magneto-structural transition responsible for the magnetocaloric effect was first order in nature.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"204 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116309476","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947943
T. Zhou, Mingsheng Zhang, H. Chung, H. S. Wong, Shikun He, Boon Hao Low, Zhejie Liu, Febiana Tjiptoharsonos
The paper discusses the magnetization dynamics of spin-torque oscillator with negative Ku under alternative head field for microwave assisted magnetic recording. Magnetization switching of spin-injection layer (SIL) is essential to have the same precession mode of the field generation layer before and after the head field change directions. The SIL needs to be properly chosen in order to have short switching time. The layer stack and material selection of spin torque oscillator (STO) is also discussed in terms of stability against the stray field. The results discussed in this paper helps to understand the design fundamentals of STO for microwave assisted magnetic recording.
{"title":"Magnetization dynamics in spin-torque oscillator with negative Ku for microwave assisted magnetic recording","authors":"T. Zhou, Mingsheng Zhang, H. Chung, H. S. Wong, Shikun He, Boon Hao Low, Zhejie Liu, Febiana Tjiptoharsonos","doi":"10.1109/MSSC.2014.6947943","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947943","url":null,"abstract":"The paper discusses the magnetization dynamics of spin-torque oscillator with negative Ku under alternative head field for microwave assisted magnetic recording. Magnetization switching of spin-injection layer (SIL) is essential to have the same precession mode of the field generation layer before and after the head field change directions. The SIL needs to be properly chosen in order to have short switching time. The layer stack and material selection of spin torque oscillator (STO) is also discussed in terms of stability against the stray field. The results discussed in this paper helps to understand the design fundamentals of STO for microwave assisted magnetic recording.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133892980","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947688
X. M. Liu, J. Ding, G. Kakazei, A. Adeyeye
Magnonic crystals (MCs), conceived as the magnetic microwave analog of photonic crystals, have received considerable attention recently due to their potential in a wide range of applications such as microwave resonators, filters and spin logic devices. Compared with conventional single component MCs, bi-component MCs consisting of arrays of one FM material in the matrix of another FM material shows advantageous due to an additional degree of freedom in tailoring spin wave properties. In this work, we present a systematic investigation of the static and dynamic behaviors of various types of 1-D and 2-D bi-component MCs.
{"title":"Static and dynamic behaviors of 1-D and 2-D magnonic crystals","authors":"X. M. Liu, J. Ding, G. Kakazei, A. Adeyeye","doi":"10.1109/MSSC.2014.6947688","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947688","url":null,"abstract":"Magnonic crystals (MCs), conceived as the magnetic microwave analog of photonic crystals, have received considerable attention recently due to their potential in a wide range of applications such as microwave resonators, filters and spin logic devices. Compared with conventional single component MCs, bi-component MCs consisting of arrays of one FM material in the matrix of another FM material shows advantageous due to an additional degree of freedom in tailoring spin wave properties. In this work, we present a systematic investigation of the static and dynamic behaviors of various types of 1-D and 2-D bi-component MCs.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129876667","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947685
V. Chaudhary, A. Chaturvedi, R. Ramanujan
We have studied the magnetocaloric effect in high energy ball milled (Fe70Ni30)95Mn5 alloy nanoparticles. The partial substitution of Fe and Ni by Mn decreases the Curie temperature of the alloy to near room temperature (338 K). Relative cooling power (RCP) increases from 26 to 470 J-kg-1 for a field change of 0.5 and 5 T, respectively, these values are comparable to the benchmark magnetocaloric material, gadolinium.
{"title":"Magnetocaloric behavior of Fe-Ni-Mn nanoparticies","authors":"V. Chaudhary, A. Chaturvedi, R. Ramanujan","doi":"10.1109/MSSC.2014.6947685","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947685","url":null,"abstract":"We have studied the magnetocaloric effect in high energy ball milled (Fe<sub>70</sub>Ni<sub>30</sub>)<sub>95</sub>Mn<sub>5</sub> alloy nanoparticles. The partial substitution of Fe and Ni by Mn decreases the Curie temperature of the alloy to near room temperature (338 K). Relative cooling power (RCP) increases from 26 to 470 J-kg<sup>-1</sup> for a field change of 0.5 and 5 T, respectively, these values are comparable to the benchmark magnetocaloric material, gadolinium.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116899095","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947690
P. Ho, G. Han, G. Chow, Jingsheng Chen
Perpendicular magnetic anisotropy L10-FePt/MgO/[Co/Pd]30 magnetic tunnel junctions (MTJs) with ultra-thin L10-FePt layer of thickness 1 to 4 nm were fabricated and studied. The ultra-thin L10-FePt behaved as the free layer while the thicker and harder [Co/Pd]30 behaved as the fixed layer. The interlayer coupling within the MTJ with L10-FePt layer thickness of 4 nm was attributed mainly to magnetostatic coupling and direct coupling due to pinholes. The magnitude of the interlayer coupling field in the L10-FePt/MgO/[Co/Pd]30 MTJ was insignificant compared to the L10-FePt based pseudo spin valves reported earlier. There was also no sign of dipolar stray field coupling, owing to the single domain characteristic property of the fixed [Co/Pd]30 layer.
{"title":"Interlayer coupling in ultra-thin L10-FePt/MgO/[Co/Pd]30 magnetic tunnel junctions","authors":"P. Ho, G. Han, G. Chow, Jingsheng Chen","doi":"10.1109/MSSC.2014.6947690","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947690","url":null,"abstract":"Perpendicular magnetic anisotropy L1<sub>0</sub>-FePt/MgO/[Co/Pd]<sub>30</sub> magnetic tunnel junctions (MTJs) with ultra-thin L1<sub>0</sub>-FePt layer of thickness 1 to 4 nm were fabricated and studied. The ultra-thin L1<sub>0</sub>-FePt behaved as the free layer while the thicker and harder [Co/Pd]<sub>30</sub> behaved as the fixed layer. The interlayer coupling within the MTJ with L1<sub>0</sub>-FePt layer thickness of 4 nm was attributed mainly to magnetostatic coupling and direct coupling due to pinholes. The magnitude of the interlayer coupling field in the L1<sub>0</sub>-FePt/MgO/[Co/Pd]<sub>30</sub> MTJ was insignificant compared to the L1<sub>0</sub>-FePt based pseudo spin valves reported earlier. There was also no sign of dipolar stray field coupling, owing to the single domain characteristic property of the fixed [Co/Pd]<sub>30</sub> layer.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131674049","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947941
Yinquan Yu, Q. Jiang, N. Aung, H. N. Phyu
In computer aided design and analysis of electrical machines, electromagnetic field problems are solved in 2 dimensional space (2D) or 3 dimensional space (3D) depending on the problem nature. This study reports the comparative analysis of computation in 2D and 3D, in terms of important machine performance indicators like average torque, varied torque and unbalanced magnetic pull. As an example, a Brushless DC (BLDC) motor is analyzed to evaluate accuracy and computational effort. The analysis highlights the difference in accuracy and the reasons for the discrepancy.
{"title":"Comparison of 2-D and 3-D EM field and force simulation accuracy in numerical environment","authors":"Yinquan Yu, Q. Jiang, N. Aung, H. N. Phyu","doi":"10.1109/MSSC.2014.6947941","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947941","url":null,"abstract":"In computer aided design and analysis of electrical machines, electromagnetic field problems are solved in 2 dimensional space (2D) or 3 dimensional space (3D) depending on the problem nature. This study reports the comparative analysis of computation in 2D and 3D, in terms of important machine performance indicators like average torque, varied torque and unbalanced magnetic pull. As an example, a Brushless DC (BLDC) motor is analyzed to evaluate accuracy and computational effort. The analysis highlights the difference in accuracy and the reasons for the discrepancy.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116074934","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947944
Zhiliang Qin, K. Cai, Yibin Ng, Songhua Zhang
In this paper, we consider iterative detection and decoding for nonbinary low-density parity-check (LDPC) coded partial-response (PR) channels with written-in errors, which are assumed to be the output of a binary symmetrical channel (BSC). We propose a symbol-level BCJR detector to produce directly soft information of nonbinary LDPC code symbols based on a sectionalized joint BSC/PR trellis. Simulation results show that the proposed receiver outperforms bit-level schemes and enables nonbinary LDPC codes to achieve noticeable performance gains over their binary counterparts.
{"title":"Iterative joint detection and decoding for nonbinary LDPC coded partial-response channels with written-in errors","authors":"Zhiliang Qin, K. Cai, Yibin Ng, Songhua Zhang","doi":"10.1109/MSSC.2014.6947944","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947944","url":null,"abstract":"In this paper, we consider iterative detection and decoding for nonbinary low-density parity-check (LDPC) coded partial-response (PR) channels with written-in errors, which are assumed to be the output of a binary symmetrical channel (BSC). We propose a symbol-level BCJR detector to produce directly soft information of nonbinary LDPC code symbols based on a sectionalized joint BSC/PR trellis. Simulation results show that the proposed receiver outperforms bit-level schemes and enables nonbinary LDPC codes to achieve noticeable performance gains over their binary counterparts.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128011062","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947933
Han Guchang, H. Jiancheng, S. C. Hin, M. Tran, Lim Sze Ter
Spin transfer torque (STT) MRAM is a promising scalable nonvolatile memory that may have fast speed, long endurance and low power consumption. In order to realize all these advantages, we first review the key requirements for storage materials with perpendicular magnetic anisotropy (PMA). STT-switching current is too high for low-power application due to low-energy efficiency. Among different types of alternative switching methods, electric field (EF) assisted switching is the most promising candidate. We proposed Oersted field guided EF switching and EF pulse width controlled switching for ellipse cells. Our experimental results show that even with an external field of ±5 Oe, the magnetization switching can be realized through applying an electric field. Our simulation results show that for ellipse cells, the bi-state switching can be controlled by EF pulse width without any external field.
{"title":"Spin transfer torque (STT) MRAM and beyond","authors":"Han Guchang, H. Jiancheng, S. C. Hin, M. Tran, Lim Sze Ter","doi":"10.1109/MSSC.2014.6947933","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947933","url":null,"abstract":"Spin transfer torque (STT) MRAM is a promising scalable nonvolatile memory that may have fast speed, long endurance and low power consumption. In order to realize all these advantages, we first review the key requirements for storage materials with perpendicular magnetic anisotropy (PMA). STT-switching current is too high for low-power application due to low-energy efficiency. Among different types of alternative switching methods, electric field (EF) assisted switching is the most promising candidate. We proposed Oersted field guided EF switching and EF pulse width controlled switching for ellipse cells. Our experimental results show that even with an external field of ±5 Oe, the magnetization switching can be realized through applying an electric field. Our simulation results show that for ellipse cells, the bi-state switching can be controlled by EF pulse width without any external field.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115687357","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947936
Zhi-Min Yuan, C. Ong, S. Ang, J. Shi, B. Santoso, S. Leong, Jack Tsai
Currently, the areal density grow in HDD still depends on the reduction of grain number per bit. In order to have less SNR penalty, it has to scale more on the track density rather than the linear density. This work proposed to insert an additional servo recording layer between data recording layer and SUL of conventional PMR media. With high quality continuous servo signals, the dedicated servo recording system has better servo performance than the conventional embedded servo for the same servo mechanics. This guarantees the high track density requirement of magnetic recording system.
{"title":"Servo layer design in dedicated servo recording system","authors":"Zhi-Min Yuan, C. Ong, S. Ang, J. Shi, B. Santoso, S. Leong, Jack Tsai","doi":"10.1109/MSSC.2014.6947936","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947936","url":null,"abstract":"Currently, the areal density grow in HDD still depends on the reduction of grain number per bit. In order to have less SNR penalty, it has to scale more on the track density rather than the linear density. This work proposed to insert an additional servo recording layer between data recording layer and SUL of conventional PMR media. With high quality continuous servo signals, the dedicated servo recording system has better servo performance than the conventional embedded servo for the same servo mechanics. This guarantees the high track density requirement of magnetic recording system.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131441915","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 : 2014-11-06DOI: 10.1109/MSSC.2014.6947938
Zhang Mingsheng, Zhu Tiejun, Yu Zhimin
The effect of the interactions between the grains on magnetic switching is analyzed by micromagnetic simulation for achieving effective magnetic switching in microwave assisted magnetic recording. The switching window of the grain with another grain of the same magnetization shifts to lower frequencies, while the switching window of the grain with another grain of opposite magnetization shrinks from both low and high frequency compared with that of the single grain. The exchange coupling between the grains is helpful in extending the switching window for the grain with another opposite magnetization grain.
{"title":"Effect of interactions between the grains on magnetic switching in microwave assisted magnetic recording","authors":"Zhang Mingsheng, Zhu Tiejun, Yu Zhimin","doi":"10.1109/MSSC.2014.6947938","DOIUrl":"https://doi.org/10.1109/MSSC.2014.6947938","url":null,"abstract":"The effect of the interactions between the grains on magnetic switching is analyzed by micromagnetic simulation for achieving effective magnetic switching in microwave assisted magnetic recording. The switching window of the grain with another grain of the same magnetization shifts to lower frequencies, while the switching window of the grain with another grain of opposite magnetization shrinks from both low and high frequency compared with that of the single grain. The exchange coupling between the grains is helpful in extending the switching window for the grain with another opposite magnetization grain.","PeriodicalId":237775,"journal":{"name":"Magnetics Symposium 2014 - Celebrating 50th Anniversary of IEEE Magnetics Society (MSSC50)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124732480","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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