The Effects of Magnetic Properties of L10-FePt/Fe Based Exchange Coupled Composite Media on Switching Field

2014 ◽  
Vol 931-932 ◽  
pp. 271-275 ◽  
Author(s):  
Warunee Tipcharoen ◽  
Arkom Kaewrawang ◽  
Apirat Siritaratiwat ◽  
Kittipong Tonmitra
Keyword(s):  
Magnetic Properties ◽  
Magnetic Recording ◽  
Exchange Coupling ◽  
Magnetocrystalline Anisotropy ◽  
Areal Density ◽  
Anisotropy Constant ◽  
Recording System ◽  
Switching Field ◽  
Magnetic Parameters ◽  
Exchange Coupled Composite

The L10-FePt/Fe based exchange coupled composite (ECC) bilayer media is one candidate to extend the areal density of magnetic recording system and solve writability issue in trilemma. L10-FePt is the great high magnetic anisotropy material. Therefore, the magnetic parameters of this material such as magnetocrystalline anisotropy constant, Ku, saturation magnetization, Ms, and exchange coupling between a soft/hard interface, are important on magnetic material properties. In this work, the effects of magnetic parameters on magnetic properties of L10-FePt/Fe based ECC bilayer media are simulated by the object oriented micromagnetic framework based on Landau-Lifshitz-Gilbert equation. The ECC bilayer media can reduce switching field, Hsw, of media lower than available writing head field. Hence, writability issues of high Ku media can be achieved. Reducing Hsw of ECC bilayer media obtains from lower Ku and higher Ms values. This work can achieve writing capability of a future magnetic recording system.

Effects of Magnetic Properties of L10-CoPt based Bit Patterned Media with Tilted-Easy Axis on Switching Field at Areal Density over 2 Tb/in2

2015 ◽  
Vol 781 ◽  
pp. 207-210
Author(s):  
Arkom Kaewrawang
Keyword(s):  
Magnetic Properties ◽  
Easy Axis ◽  
Magnetocrystalline Anisotropy ◽  
Areal Density ◽  
Anisotropy Constant ◽  
Magnetic Media ◽  
Switching Field ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Easy Direction

Decrease of a switching field, Hsw, of the magnetic media with high magnetocrystalline anisotropy constant, Ku, can be handled by tilted-easy axis. Not only tilting easy direction of crystal but also optimum magnetic properties can improve writability. The effects of Ku and saturation magnetization, Ms, of L10-CoPt material of BPM with 45° tilted-easy axis are investigated in this article. The object oriented micromagnetic framework package based on Landau - Lifshitz - Gilbert equation has been used to analyze the magnetic properties of media in this paper. The results indicate that the Hsw decreases with decreasing Ku and increasing Ms. To achieve the Hsw lower than the maximum write head field, the Ku and Ms values should not be over 1.30 MJ/m3 and should exceed 0.30 MA/m, respectively.

Role of Intergrain and Intragrain Coupling on Switching Field of Granular Exchange Coupled Composite Media Using Microwave Assisted Magnetic Recording

2015 ◽  
Vol 781 ◽  
pp. 211-214
Author(s):  
Naruemon Wannawong ◽  
Arkom Kaewrawang ◽  
Kotchakorn Pituso ◽  
Warunee Tipcharoen ◽  
Apirat Siritaratiwat
Keyword(s):  
Hard Disk Drive ◽  
Magnetic Recording ◽  
Exchange Coupling ◽  
Microwave Field ◽  
Hard Disk ◽  
Areal Density ◽  
Disk Drive ◽  
Switching Field ◽  
Microwave Assisted

Microwave assisted magnetic recording is one interesting magnetic recording technology to improve writability for high areal density of hard disk drive. In this work, the role of intergrain and intragrain coupling and microwave field is investigated by micromagnetic simulation based on the Landau - Lifshitz - Gilbert equation. The results show that the switching field, Hsw, of media with microwave field, Hac, of 10 GHz is lower than that for media without Hac. The exchange coupling between nearest neighbor grains hardly affects the Hsw of media and slightly affects the slope of hysteresis loop. In addition, the slope of hysteresis loops and Hsw decrease with increasing exchange coupling in each grain. The results from this work can lead to obtain the improvement writability and increasing areal density of hard disk drive.

New Method of Areal Density Capability Determination for Digital Magnetic Recording System

2011 ◽  
Vol 47 (10) ◽  
pp. 3312-3315 ◽  
Author(s):  
Xinzhi Xing ◽  
Davide Guarisco ◽  
Guang Yang ◽  
Zhihao Li ◽  
Kroum Stoev ◽  
...  
Keyword(s):  
Magnetic Recording ◽  
Areal Density ◽  
Recording System ◽  
New Method

scholarly journals Micromagnetic Simulation of L10-FePt-Based Exchange-Coupled-Composite-Bit-Patterned Media with Microwave-Assisted Magnetic Recording at Ultrahigh Areal Density

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1264
Author(s):  
Pirat Khunkitti ◽  
Naruemon Wannawong ◽  
Chavakon Jongjaihan ◽  
Apirat Siritaratiwat ◽  
Anan Kruesubthaworn ◽  
...  
Keyword(s):  
Magnetic Recording ◽  
Magnetic Domain ◽  
Hysteresis Loops ◽  
Areal Density ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Microwave Assisted ◽  
The Media ◽  
5 Ghz ◽  
Exchange Coupled Composite

In this work, we propose exchange-coupled-composite-bit-patterned media (ECC-BPM) with microwave-assisted magnetic recording (MAMR) to improve the writability of the magnetic media at a 4 Tb/in2 recording density. The suitable values of the applied microwave field’s frequency and the exchange coupling between magnetic dots, Adot, of the proposed media were evaluated. It was found that the magnitude of the switching field, Hsw, of the bilayer ECC-BPM is significantly lower than that of a conventional BPM. Additionally, using the MAMR enables further reduction of Hsw of the ECC-BPM. The suitable frequency of the applied microwave field for the proposed media is 5 GHz. The dependence of Adot on the Hsw was additionally examined, showing that the Adot of 0.14 pJ/m is the most suitable value for the proposed bilayer ECC-BPM. The physical explanation of the Hsw of the media under a variation of MAMR and Adot was given. Hysteresis loops and the magnetic domain of the media were characterized to provide further details on the results. The lowest Hsw found in our proposed media is 12.2 kOe, achieved by the bilayer ECC-BPM with an Adot of 0.14 pJ/m using a 5 GHz MAMR.

Microwave Assisted Magnetization Reversal on Exchange Coupled Composite Media

2014 ◽  
Vol 931-932 ◽  
pp. 1265-1269 ◽  
Author(s):  
Naruemon Wannawong ◽  
Warunee Tipcharoen ◽  
Arkom Kaewrawang
Keyword(s):  
Magnetic Recording ◽  
Magnetization Reversal ◽  
Microwave Field ◽  
Single Layer ◽  
Microwave Frequency ◽  
Areal Density ◽  
Disk Drive ◽  
Microwave Assisted ◽  
Superparamagnetic Limit ◽  
Exchange Coupled Composite

To overcome superparamagnetic limit, microwave assisted magnetic recording (MAMR) is one interesting magnetic recording technology. Therefore, the effect of microwave on magnetization reversal in media should be analyzed. In this work, we propose the MAMR to decrease switching field (coercivity, Hsw) in exchange coupled composite (ECC) media by using the micromagnetic simulation based on the Landau - Lifshitz - Gilbert equation. The Hsw of single layer and ECC media without microwave field is 110.90 and 7.7 kOe, respectively. When the oscillating microwave field is added, Hsw of single layer media with microwave frequency of 2.5 - 40 GHz is lower than 110.90 kOe. Likewise, Hsw of ECC media with microwave frequency of 5 - 16 GHz is lower than 7.7 kOe and has the lowest value of 4.9 kOe at frequency of 10 GHz. The results from this work lead to solve superparamagnetic limit and increase areal density in hard disk drive.

Investigation on Magnetic Properties of L10-FePt/Fe Graded Media Multilayer

2013 ◽  
Vol 802 ◽  
pp. 189-193 ◽  
Author(s):  
Warunee Tipcharoen ◽  
Arkom Kaewrawang ◽  
Apirat Siritaratiwat ◽  
Kittipong Tonmitra
Keyword(s):  
Magnetic Properties ◽  
Hysteresis Loop ◽  
Magnetic Energy ◽  
Magnetic Domain ◽  
Single Layer ◽  
Anisotropy Constant ◽  
Switching Field ◽  
Preferred Direction ◽  
Data Density ◽  
High Grading

To improve writing capability of high magnetic anisotropy medium - L10-FePt, graded medium multilayer is one key candidate. Therefore, investigation of magnetic material properties of graded media multilayer is essential. In this work, we focus on magnetic properties of L10-FePt/Fe graded media multilayer such as hysteresis loop, magnetic energy and magnetic domain by the micromagnetic simulation the object oriented micromagnetic framework software based on the Landau - Lifshitz - Gilbert equation. The graded media multilayer can achieve reducing the switching field, Hsw, below available writing head field with high thermal stability. The anisotropy energy in graded media is higher than single layer and bilayer media that results in unstable magnetization in preferred direction. The proposed graded (f) and (g) structures are high grading magnetocrystalline anisotropy constant, Ku, that can reduce Hsw below single layer, bilayer and available writing head field. The hysteresis loop of low grading Ku structures has different steps; however, it disappear with high grading Ku structures of graded (e) - (g) structures. They have narrow loop compared with single layer. The results from this work lead to improve magnetic trilemma issue and increase data density.

scholarly journals Design and Micromagnetic Simulation of Fe/L10-FePt/Fe Trilayer for Exchange Coupled Composite Bit Patterned Media at Ultrahigh Areal Density

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Warunee Tipcharoen ◽  
Arkom Kaewrawang ◽  
Apirat Siritaratiwat
Keyword(s):  
Exchange Coupling ◽  
Single Layer ◽  
Areal Density ◽  
Interlayer Exchange Coupling ◽  
Magnetic Media ◽  
Recording Technology ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Interlayer Exchange ◽  
Exchange Coupled Composite

Exchange coupled composite bit patterned media (ECC-BPM) are one candidate to solve the trilemma issues, overcome superparamagnetic limitations, and obtain ultrahigh areal density. In this work, the ECC continuous media and ECC-BPM of Fe/L10-FePt/Fe trilayer schemes are proposed and investigated based on the Landau-Lifshitz-Gilbert equation. The switching field,Hsw, of the hard phase in the proposed continuous ECC trilayer media structure is reduced below the maximum write head field at interlayer exchange coupling between hard and soft phases,Aex, higher than 20 pJ/m and its value is lower than that for continuousL10-FePt single layer media andL10-FePt/Fe bilayer. Furthermore, theHswof the proposed ECC-BPM is lower than the maximum write head field with exchange coupling coefficient between neighboring dots of 5 pJ/m andAexover 10 pJ/m. Therefore, the proposed ECC-BPM trilayer has the highest potential and is suitable for ultrahigh areal density magnetic recording technology at ultrahigh areal density. The results of this work may be gainful idea for nanopatterning in magnetic media nanotechnology.

Magnetic Properties of CoFeB-SiO2 Nanocomposite and [(Co40Fe40B20)X(SiO2)100-X /α-Si:H]n Multilayer Films

2012 ◽  
Vol 190 ◽  
pp. 466-469 ◽  
Author(s):  
Elena A. Denisova ◽  
Rauf S. Iskhakov ◽  
Lidia Chekanova ◽  
Yuri Kalinin ◽  
Alexander Sitnikov
Keyword(s):  
Magnetic Properties ◽  
Exchange Coupling ◽  
Magnetic Measurements ◽  
Composite Films ◽  
Multilayer Films ◽  
Nanocomposite Films ◽  
Phase Content ◽  
Granular Films ◽  
Magnetic Parameters ◽  
Ferromagnetic Exchange

Magnetic properties of (Co40Fe40B20)X(SiO2)100-X nanogranular composite films, [(Co40Fe40B20)X(SiO2)100-X /a-Si:n multilayer films and layered (Co40Fe40B20)X(SiO2)100-X films with X ranging from 30 to 80 have been characterized by means of magnetic measurements and ferromagnetic resonance. Layer thickness was varied between 1.3 and 6 nm. Thermal decrease of (Co40Fe40B20)X(SiO2)100-X composite magnetization follows the T3/2 law. The spectrum of standing spin-wave has been detected in the perpendicular experiment configuration for films with the metal phase content above 48 vol. %. It is found that the Hr(n2) dependencies are non-linear. Such behavior is probably caused by the fluctuations of magnetic parameters (the magnetization and the ferromagnetic exchange coupling) in nanocomposite films. A comparison between the magnetic properties of (Co40Fe40B20)X(SiO2)100-X granular films and [(Co40Fe40B20)X(SiO2)100-X /a-Si:n multilayer films was carried out.

scholarly journals Large and sensitive magnetostriction in ferromagnetic composites with nanodispersive precipitates

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Junming Gou ◽  
Tianyu Ma ◽  
Xiaolian Liu ◽  
Changsheng Zhang ◽  
Liangwei Sun ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Magnetocrystalline Anisotropy ◽  
Large Strain ◽  
Anisotropy Constant ◽  
The Body ◽  
Saturation Magnetostriction ◽  
Switching Field ◽  
The Matrix ◽  
Face Centered ◽  
The One

AbstractLarge and sensitive magnetostriction (large strain induced by small magnetic fields) is highly desired for applications of magnetostrictive materials. However, it is difficult to simultaneously improve magnetostriction and reduce the switching field because magnetostriction and the switching field are both proportional to the magnetocrystalline anisotropy. To solve this fundamental challenge, we report that introducing tetragonal nanoprecipitates into a cubic matrix can facilitate large and sensitive magnetostriction even in random polycrystals. As exhibited in a proof-of-principle reference, Fe–Ga alloys, the figure of merit—defined by the saturation magnetostriction over the magnetocrystalline anisotropy constant—can be enhanced by over 5-fold through optimum aging of the solution-treated precursor. On the one hand, the aging-induced nanodispersive face-centered tetragonal (FCT) precipitates create local tetragonal distortion of the body-centered cubic (BCC) matrix, substantially enhancing the saturation magnetostriction to be comparable to that of single crystal materials. On the other hand, these precipitates randomly couple with the matrix at the nanoscale, resulting in the collapse of net magnetocrystalline anisotropy. Our findings not only provide a simple and feasible approach to enhance the magnetostriction performance of random polycrystalline ferromagnets but also provide important insights toward understanding the mechanism of heterogeneous magnetostriction.

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