Pub Date : 2022-08-01DOI: 10.1109/TMRC56419.2022.9918540
M. A. Bashir, Anna Zheng, A. Goncharov, P. V. Heijden, Suping Song, Ya-Jun Wei, T. Lam, R. Shi, Lijie Guan
Energy assisted perpendicular magnetic recording (ePMR) technology was utilized to ship 18–20 TB hard disk drive (HDD) by Western Digital in 2020 and is considered to be the technology for the future nearline products [1]–[2]. Magnetic writer used in ePMR technology carry the DC current by utilizing main pole (MP) and trailing side shield (TS) as lead structure connected through a small stack inside the trailing side gap region. DC current flow inside the magnetic writer volume helps improve flux jitter [3].
{"title":"DC Current Path Optimization for Energy-Assisted Magnetic Recording","authors":"M. A. Bashir, Anna Zheng, A. Goncharov, P. V. Heijden, Suping Song, Ya-Jun Wei, T. Lam, R. Shi, Lijie Guan","doi":"10.1109/TMRC56419.2022.9918540","DOIUrl":"https://doi.org/10.1109/TMRC56419.2022.9918540","url":null,"abstract":"Energy assisted perpendicular magnetic recording (ePMR) technology was utilized to ship 18–20 TB hard disk drive (HDD) by Western Digital in 2020 and is considered to be the technology for the future nearline products [1]–[2]. Magnetic writer used in ePMR technology carry the DC current by utilizing main pole (MP) and trailing side shield (TS) as lead structure connected through a small stack inside the trailing side gap region. DC current flow inside the magnetic writer volume helps improve flux jitter [3].","PeriodicalId":432413,"journal":{"name":"2022 IEEE 33rd Magnetic Recording Conference (TMRC)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129953653","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 : 2022-08-01DOI: 10.1109/TMRC56419.2022.9918619
Y. Nakamura, Taisei Akamatsu, Madoka Nishikawa, Y. Okamoto
The tolerance for burst error of the interleaved low-density parity-check (LDPC) code is evaluated with the cross-interleaved Reed-Solomon code (CIRC) in the magnetic tape drive using a BaFe magnetic tape. We evaluate the interleaved LDPC coding and iterative decoding system with burst error detector (LDPC-BD) system by required signal-to-noise ratio (SNR) to achieve “No errors” for the burst-like deterioration such as media defects to the CIRC with erasure error correction (CIRC-EC) system by computer simulation. The results clarify that the LDPC-BD system tolerates the longer burst error than the CIRC-EC system. In addition, they also clarified that the LDPC-BD system achieves “No errors” with the 3.0-4.5 dB lower SNR than the CIRC-EC system.
{"title":"Performance Evaluation of Burst Error Correction by LDPC Coding and Iterative Decoding System in Magnetic Tape Drive Using a BaFe Magnetic Tape","authors":"Y. Nakamura, Taisei Akamatsu, Madoka Nishikawa, Y. Okamoto","doi":"10.1109/TMRC56419.2022.9918619","DOIUrl":"https://doi.org/10.1109/TMRC56419.2022.9918619","url":null,"abstract":"The tolerance for burst error of the interleaved low-density parity-check (LDPC) code is evaluated with the cross-interleaved Reed-Solomon code (CIRC) in the magnetic tape drive using a BaFe magnetic tape. We evaluate the interleaved LDPC coding and iterative decoding system with burst error detector (LDPC-BD) system by required signal-to-noise ratio (SNR) to achieve “No errors” for the burst-like deterioration such as media defects to the CIRC with erasure error correction (CIRC-EC) system by computer simulation. The results clarify that the LDPC-BD system tolerates the longer burst error than the CIRC-EC system. In addition, they also clarified that the LDPC-BD system achieves “No errors” with the 3.0-4.5 dB lower SNR than the CIRC-EC system.","PeriodicalId":432413,"journal":{"name":"2022 IEEE 33rd Magnetic Recording Conference (TMRC)","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123991796","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 : 2022-08-01DOI: 10.1109/TMRC56419.2022.9918160
Seongkwon Jeong, Jaejin Lee
Bit-patterned media recording (BPMR) has been considered as a one of the key technologies to extend recording densities to 1 Tb/in2 and beyond. However, BPMR system encounters challenges of not only two-dimensional intersymbol interference but also track mis-registration (TMR). In this paper, we propose a TMR estimator based on K-means algorithm for estimating the TMR levels and prevent the performance degradation of the BPMR system. The TMR estimator calculates the distance between the centroid of readback signal and the predetermined centroids according to TMR level, and equalizer coefficients and partial response target are adjusted to the corresponding TMR level.
{"title":"Track Mis-Registration Estimator Based on K-Means Algorithm for Bit-Patterned Media Recording","authors":"Seongkwon Jeong, Jaejin Lee","doi":"10.1109/TMRC56419.2022.9918160","DOIUrl":"https://doi.org/10.1109/TMRC56419.2022.9918160","url":null,"abstract":"Bit-patterned media recording (BPMR) has been considered as a one of the key technologies to extend recording densities to 1 Tb/in2 and beyond. However, BPMR system encounters challenges of not only two-dimensional intersymbol interference but also track mis-registration (TMR). In this paper, we propose a TMR estimator based on K-means algorithm for estimating the TMR levels and prevent the performance degradation of the BPMR system. The TMR estimator calculates the distance between the centroid of readback signal and the predetermined centroids according to TMR level, and equalizer coefficients and partial response target are adjusted to the corresponding TMR level.","PeriodicalId":432413,"journal":{"name":"2022 IEEE 33rd Magnetic Recording Conference (TMRC)","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132012085","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 : 2022-08-01DOI: 10.1109/TMRC56419.2022.9918608
Xiaoyong Liu, Daniele Marui, G. Albuquerque, C. Shang, L. Wang, Z. Diao, Yuan-kai Zheng, Chih-Ching Hu, Yung-Hung Wang, Hongxue Liu, Guanxiong Li, Anup Roy, C. Chien, M. Mao, J. Freitag, Yukimasa Okada, Yunfei Li
HDD areal density growth poses significant challenges on head and media and HDI developments. In this paper, we review a novel reader design - dual free layer (DFL) to address current limitations from spin-valve based single free layer (SFL) reader head. DFL reader heads with narrower RG down to 14nm and trackwidth down to 20nm have been successfully fabricated with good stability. Magnetic recording test shows over 4% linear resolution improvement and up to 0.1 order bit-error-rate reduction over SFL. This result indicates DFL reader designs are robust and attractive candidates for novel reader suitable for sustaining HDD areal density growth beyond 2Tb/in2.
{"title":"Dual Free Layer Reader for Future Recording Head","authors":"Xiaoyong Liu, Daniele Marui, G. Albuquerque, C. Shang, L. Wang, Z. Diao, Yuan-kai Zheng, Chih-Ching Hu, Yung-Hung Wang, Hongxue Liu, Guanxiong Li, Anup Roy, C. Chien, M. Mao, J. Freitag, Yukimasa Okada, Yunfei Li","doi":"10.1109/TMRC56419.2022.9918608","DOIUrl":"https://doi.org/10.1109/TMRC56419.2022.9918608","url":null,"abstract":"HDD areal density growth poses significant challenges on head and media and HDI developments. In this paper, we review a novel reader design - dual free layer (DFL) to address current limitations from spin-valve based single free layer (SFL) reader head. DFL reader heads with narrower RG down to 14nm and trackwidth down to 20nm have been successfully fabricated with good stability. Magnetic recording test shows over 4% linear resolution improvement and up to 0.1 order bit-error-rate reduction over SFL. This result indicates DFL reader designs are robust and attractive candidates for novel reader suitable for sustaining HDD areal density growth beyond 2Tb/in2.","PeriodicalId":432413,"journal":{"name":"2022 IEEE 33rd Magnetic Recording Conference (TMRC)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126888996","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 : 2022-08-01DOI: 10.1109/TMRC56419.2022.9918551
Amirhossein Sayyafan, Ahmed Aboutaleb, B. Belzer, K. Sivakumar, S. Greaves, K. Chan, Ashish James
This paper presents a turbo-detection system consisting of a convolutional neural network (CNN) based equalizer, a Bahl-Cocke-Jelinek-Raviv (BCJR) trellis detector, a CNN-based media noise predictor (MNP), and a low-density parity-check (LDPC) channel decoder for two-dimensional magnetic recording (TDMR). The BCJR detector, CNN MNP, and LDPC decoder iteratively exchange soft information to maximize the areal density (AD) subject to a bit error rate (BER) constraint. Simulation results employing a realistic grain switching probabilistic (GSP) media model show that the proposed system is quite robust to track-misregistration (TMR). Compared to a I-D pattern-dependent noise prediction (PDNP) baseline with soft intertrack interference (ITI) subtraction, the system achieves 0.34% AD gain with read-TMR alone and 0.69% with write- and read-TMR together.
{"title":"Convolutional Neural Network-based Media Noise Prediction and Equalization for TDMR Turbo-detection with Write/Read TMR","authors":"Amirhossein Sayyafan, Ahmed Aboutaleb, B. Belzer, K. Sivakumar, S. Greaves, K. Chan, Ashish James","doi":"10.1109/TMRC56419.2022.9918551","DOIUrl":"https://doi.org/10.1109/TMRC56419.2022.9918551","url":null,"abstract":"This paper presents a turbo-detection system consisting of a convolutional neural network (CNN) based equalizer, a Bahl-Cocke-Jelinek-Raviv (BCJR) trellis detector, a CNN-based media noise predictor (MNP), and a low-density parity-check (LDPC) channel decoder for two-dimensional magnetic recording (TDMR). The BCJR detector, CNN MNP, and LDPC decoder iteratively exchange soft information to maximize the areal density (AD) subject to a bit error rate (BER) constraint. Simulation results employing a realistic grain switching probabilistic (GSP) media model show that the proposed system is quite robust to track-misregistration (TMR). Compared to a I-D pattern-dependent noise prediction (PDNP) baseline with soft intertrack interference (ITI) subtraction, the system achieves 0.34% AD gain with read-TMR alone and 0.69% with write- and read-TMR together.","PeriodicalId":432413,"journal":{"name":"2022 IEEE 33rd Magnetic Recording Conference (TMRC)","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125680800","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 : 2022-08-01DOI: 10.1109/TMRC56419.2022.9918577
Yabin Fan
Spintronics research based on topological insulators (TIs) has shown rapid progress during the past decade. Due to the strong spin-orbit coupling (SOC) and particularly the spin-momentum locked Dirac states on the surface, TIs are expected to be very promising materials for spintronic applications ranging from ultralow power memory/logic devices to new ultrafast computation technologies. In this digest, I will review the progress on TI-based spintronics. In particular, I will review the experiments on magnetization switching through giant spin-orbit torques (SOT) in various TI-based magnetic systems. The SOT efficiency and switching features in these structures will be discussed. The large SOT and efficient current-induced magnetization switching exhibited by the TI-based structures may lead to innovative spintronic applications such as ultralow-power dissipation memory/logic devices.
{"title":"Topological Insulators for Efficient Spin-Orbit Torques","authors":"Yabin Fan","doi":"10.1109/TMRC56419.2022.9918577","DOIUrl":"https://doi.org/10.1109/TMRC56419.2022.9918577","url":null,"abstract":"Spintronics research based on topological insulators (TIs) has shown rapid progress during the past decade. Due to the strong spin-orbit coupling (SOC) and particularly the spin-momentum locked Dirac states on the surface, TIs are expected to be very promising materials for spintronic applications ranging from ultralow power memory/logic devices to new ultrafast computation technologies. In this digest, I will review the progress on TI-based spintronics. In particular, I will review the experiments on magnetization switching through giant spin-orbit torques (SOT) in various TI-based magnetic systems. The SOT efficiency and switching features in these structures will be discussed. The large SOT and efficient current-induced magnetization switching exhibited by the TI-based structures may lead to innovative spintronic applications such as ultralow-power dissipation memory/logic devices.","PeriodicalId":432413,"journal":{"name":"2022 IEEE 33rd Magnetic Recording Conference (TMRC)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123452802","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 : 2022-08-01DOI: 10.1109/TMRC56419.2022.9918565
T. Nguyen, Jaejin Lee
In bit patterned media recording (BPMR) technology, data are stored on the magnetic islands. Thus, for increasing the areal density (AD), we have to reduce the distance between magnetic islands. This makes the islands be influenced by the neighboring islands, which is the two-dimensional (2D) inter-symbol interference (ISI), i.e. the inter-symbol interference (ISI) and inter-track interference (ITI) from the cross-and down-track directions, respectively.
{"title":"Iterative parallel-serial detection structure using MAP algorithm for bit-patterned media recording systems","authors":"T. Nguyen, Jaejin Lee","doi":"10.1109/TMRC56419.2022.9918565","DOIUrl":"https://doi.org/10.1109/TMRC56419.2022.9918565","url":null,"abstract":"In bit patterned media recording (BPMR) technology, data are stored on the magnetic islands. Thus, for increasing the areal density (AD), we have to reduce the distance between magnetic islands. This makes the islands be influenced by the neighboring islands, which is the two-dimensional (2D) inter-symbol interference (ISI), i.e. the inter-symbol interference (ISI) and inter-track interference (ITI) from the cross-and down-track directions, respectively.","PeriodicalId":432413,"journal":{"name":"2022 IEEE 33rd Magnetic Recording Conference (TMRC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128594052","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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