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Chin. Phys. B, 2023, Vol. 32(2): 026803    DOI: 10.1088/1674-1056/ac9fc1

High repetition granular Co/Pt multilayers with improved perpendicular remanent magnetization for high-density magnetic recording

Zhi Li(李智)1,2, Kun Zhang(张昆)1,2,†, Ao Du(杜奥)1, Hongchao Zhang(张洪超)1,2, Weibin Chen(陈伟斌)3, Ning Xu(徐宁)1,2, Runrun Hao(郝润润)2, Shishen Yan(颜世申)3, Weisheng Zhao(赵巍胜)1,2, and Qunwen Leng(冷群文)1,2
1 Fert Beijing Research Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China;
2 Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute, Beihang University, Qingdao 266101, China;
3 School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
Abstract  Thanks to the strong perpendicular magnetic anisotropy (PMA), excellent processing compatibility as well as novel spintronic phenomenon, Co/Pt multilayers have been attracting massive attention and widely used in magnetic storage. However, reversed magnetic domains come into being with the increasing layer repetition ‘$N$’ to reduce magneto-static energy, resulting in the remarkable diminishment of the remanent magnetization ($M_{\rm r}$). As a result, the product of $M_{\rm r}$ and thickness ($i.e.$, the remanent moment-thickness product, $M_{\rm r}t$), a key parameter in magnetic recording for reliable data storing and reading, also decreases dramatically. To overcome this issue, we deposit an ultra-thick granular [Co/Pt]$_{80}$ multilayer with a total thickness of 68 nm on granular SiN$_{x}$ buffer layer. The $M_{\rm r}t$ value, $M_{\rm r}$ to saturation magnetization ($M_{\rm s}$) ratio as well as out of plane (OOP) coercivity ($H_{\rm coop}$) are high up to 2.97 memu/cm$^{2}$, 67%, and 1940 Oe (1 Oe = 79.5775 A$\cdot$m$^{-1}$), respectively, which is remarkably improved compared with that of continuous [Co/Pt]$_{80}$ multilayers. That is because large amounts of grain boundaries in the granular multilayers can efficiently impede the propagation and expansion of reversed magnetic domains, which is verified by experimental investigations and micromagnetic simulation results. The simulation results also indicate that the value of $M_{\rm r}t$, $M_{\rm r}/M_{\rm s}$ ratio, and $H_{\rm coop}$ can be further improved through optimizing the granule size, which can be experimentally realized by manipulating the process parameter of SiN$_{x}$ buffer layer. This work provides an alternative solution for achieving high $M_{\rm r}t$ value in ultra-thick Co/Pt multilayers, which is of unneglectable potential in applications of high-density magnetic recording.
Keywords:  granular Co/Pt multilayers      perpendicular magnetic anisotropy      remanent moment-thickness product      magnetic recording  
Received:  07 September 2022      Revised:  24 October 2022      Accepted manuscript online:  03 November 2022
PACS:  68.65.Ac (Multilayers)  
  68.65.Cd (Superlattices)  
  75.50.Ss (Magnetic recording materials)  
  75.60.Jk (Magnetization reversal mechanisms)  
Fund: Project supported by the National Natural Science Foundation of China (Grant No. 51901008) and the National Key Research and Development Program of China (Grant No. 2021YFB3201800).
Corresponding Authors:  Kun Zhang     E-mail:

Cite this article: 

Zhi Li(李智), Kun Zhang(张昆), Ao Du(杜奥), Hongchao Zhang(张洪超), Weibin Chen(陈伟斌), Ning Xu(徐宁), Runrun Hao(郝润润), Shishen Yan(颜世申), Weisheng Zhao(赵巍胜), and Qunwen Leng(冷群文) High repetition granular Co/Pt multilayers with improved perpendicular remanent magnetization for high-density magnetic recording 2023 Chin. Phys. B 32 026803

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