Article
Materials Science, Multidisciplinary
I. Suzuki, T. Abe, H. Sepehri-Amin, K. Hono, Y. K. Takahashi
Summary: Increasing the grain density of FePt is essential for achieving an ultra-high recording density in heat-assisted magnetic recording. The highest grain density in FePt-Cr2O3 granular thin films was achieved by using a densified FePt nucleation layer. The reduced magnetic properties were attributed to the grain shape and the effect of elemental diffusion at the FePt/Cr2O3 interface. The equilibrium shape of FePt grains indicates that the solid-liquid interfacial energy is a key factor in controlling the microstructures.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Bing Zhou, B. S. D. C. S. Varaprasad, Chengchao Xu, Ming-Huang Huang, David E. Laughlin, Jian-Gang Zhu
Summary: In this study, FePt/FePt-BN/FePt-SiOx and FePt/FePt-C materials were fabricated for heat-assisted magnetic recording. The FePt/FePt-BN/FePt-SiOx media exhibited higher grain areal density and smaller grain-to-grain pitch distance, and could suppress the bimodal grain-size distribution. Both media showed good magnetic properties on Corning Lotus NXT glass substrates.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Physics, Applied
Daiki Isurugi, Takashi Saito, Shun Kaneko, Kim Kong Tham, Tomoyuki Ogawa, Shin Saito
Summary: This study evaluated the blocking temperature (T (B)) and blocking temperature distribution (Delta T (B)) of magnetic grains in L1(0)-type FePt granular films with different grain boundary materials (GBMs). T (B) and Delta T (B) were measured from remanent magnetization. The relationship between the degree of order and Curie temperature (T (C)) for the L1(0)-type FePt phase was separately evaluated using alloy films. The obtained mean T (B), mean T (B)/T (C), and Delta T (B) for granular films with SnO GBM were 620 K, 0.83 K, and 200 K, respectively, while for granular films with TiO2 GBM, they were 450 K, 0.61 K, and 260 K, respectively. Based on these values, mean T (B), mean T (B)/T (C), and Delta T (B) were calculated assuming a relaxation time of 2 x 10(-7) s, which corresponds to HAMR writing time. For SnO GBM film, these values were 737 K, 0.98 K, and 24 K, respectively, and for TiO2 GBM film, they were 685 K, 0.93 K, and 72 K, respectively. These results for granular films can be useful for designing a hard disk drive with HAMR.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Review
Physics, Applied
I. Suzuki, Y. K. Takahashi
Summary: To achieve high areal density in hard disk drives, ultrafine FePt grains and high grain density are required. While there have been studies on reducing the grain size, there are limited reports on controlling grain density. This research focused on three aspects of surface morphology and grain density, and found that maximizing the number of nucleation sites and considering surface free energy and lattice mismatch are crucial for controlling grain density.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Chuhan Sha, Limei Yang, Julie M. Cairney, Jianqiang Zhang, David J. Young
Summary: Fe-30Cr (wt%) alloy was exposed to Ar-0.5%SO2 and Ar-10%H2O-0.5%SO2 gases at 650 degrees C, forming Cr2O3 scales. Sulphur enrichment and scattered Cr-sulphides were observed at the scale-alloy interface in dry SO2 for 20 h, along with internal Cr-sulphide precipitates. After 100 h, sulphur disappeared from the interface, while more internal Cr-sulphides were produced. In wet SO2, sulphur enrichment and Cr-sulphides were maintained in both times, but no internal sulphidation was seen. Atom probe analysis revealed sulphur enrichment on chromia grain boundaries in both gases, more pronounced in wet SO2. These effects are discussed in terms of chromia grain boundary diffusion.
Article
Nanoscience & Nanotechnology
B. S. D. Ch. S. Varaprasad, Chengchao Xu, Ming-Huang Huang, David E. Laughlin, Jian-Gang Zhu
Summary: Fabricating highly ordered tall L1(0)-FePt with a small grain pitch distance on a commercially available glass substrate is crucial for heat-assisted magnetic recording (HAMR) media in industrial manufacture. Researchers achieved tall FePt grains surrounded by crystalized h-BN on Corning NXT (TM) glass through deposition at elevated temperatures in the presence of radio frequency (RF) bias. The study discusses the effect of deposition temperature on the order parameter of L1(0)-FePt-BN granular media and achieved well-isolated granular media with a high order parameter and perpendicular coercivity.
Article
Chemistry, Inorganic & Nuclear
Jonas Jacobs, James R. Hester, Stefan G. Ebbinghaus
Summary: Highly fluorinated cuprate Ruddlesden-Popper oxyfluorides La2Cu0.8Ni0.2O3F2 and La2CuO3F2 were obtained by topochemical reaction. The crystal structures of both oxyfluorides were investigated, and the reasons for the lowered symmetry were found. The formation reaction of La2CuO3F2 and its reaction intermediates were studied. La2Cu0.8Ni0.2O3F2 showed antiferromagnetic behavior, while La2CuO3F2 exhibited weak saturation moment and weak ferrimagnetic properties.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Danyu Cui, Xiao Liu, Tianhao Wu, Xuesong Lin, Xinhui Luo, Yongzhen Wu, Hiroshi Segawa, Xudong Yang, Yiqiang Zhang, Yanbo Wang, Liyuan Han
Summary: The use of cold precursor solution to control the crystallization process of tin perovskite solar cells results in highly oriented films with larger grains, leading to an increase in open-circuit voltage and overall power conversion efficiency.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Chuanzhi Liu, Zhao Dong, Qunshou Wang, Zheng Jian, Xiangying Meng, Xu Min, Wenli Pei
Summary: This study investigated the effects of Bi element on FePt using first principle density functional theory, and found that Bi can significantly reduce the ordering transition temperature of FePt and promote ordering transition mainly through affecting the vacancy mechanism.
RARE METAL MATERIALS AND ENGINEERING
(2022)
Article
Physics, Applied
Takashi Saito, Kim Kong Tham, Ryosuke Kushibiki, Tomoyuki Ogawa, Shin Saito
Summary: The study analyzed the structure of FePt grains with c-axes parallel to the film plane and their impact on magnetic properties. It was found that in-plane grains had similar structural characteristics to normal grains, and perpendicular magnetic anisotropy depended on the ratio of in-plane to normal grains as well as the degree of order. The magnetocrystalline anisotropy for perfectly ordered FePt grains was estimated to be 3.43 x 10(7) erg cm(-3).
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Daiki Isurugi, Gento Tanaka, Takashi Saito, Kim Kong Tham, Tomoyuki Ogawa, Shin Saito
Summary: In this study, post-annealing under NH3 gas atmosphere was conducted to promote the two-phase separation of FePt-BN granular films. The results showed that increasing post-annealing time led to an increase in saturation magnetization, a change in the orientation of FePt grains, and a decrease in unit cell volume of FePt grains in the granular film. The reduction in saturation magnetization for FePt-BN granular films was considered to be caused by the solid solution of B in the FePt grains.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Plant Sciences
Wei He, Wanjing Li, Xiao Luo, Yuqin Tang, Long Wang, Feng Yu, Qinlu Lin
Summary: FERONIA-LIKE RECEPTOR 3 (FLR3) and FERONIA-LIKE RECEPTOR 14 (FLR14) are two important regulators of grain chalkiness and quality in rice. They positively regulate grain quality by maintaining endosperm redox homeostasis and alleviating endosperm oxidative stress caused by high temperature.
JOURNAL OF EXPERIMENTAL BOTANY
(2023)
Article
Agronomy
Haojie Li, Naikun Kuang, Qishu Gou, Yuzhao Ma, Quanqi Li
Summary: The study found that biodegradable black film mulching is a feasible measure to improve the photosynthetic capacity and yield of maize in the North China Plain.
ARCHIVES OF AGRONOMY AND SOIL SCIENCE
(2021)
Article
Physics, Applied
Kim Kong Tham, Ryosuke Kushibiki, Shin Saito
Summary: By depositing FePt-30vol%TiN while flowing N-2 gas, the magnetic properties and nanostructure are investigated. The addition of N-2 gas leads to a reduction in lattice constant ratio and unit cell volume, as well as an increase in the degree of order of the granular film. This is due to the segregation of Ti into grain boundaries through nitridization of Ti dissolved in the FePt grains, resulting in enhanced magnetic properties of the granular film.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Weijie Yu, Weijiu Huang, Junjun Wang, Yongyao Su, Qian Long, Linqing Wang, Liangfeng Zhu
Summary: The study synthesized a silicon-gradually-doped diamond-like carbon film and analyzed its properties using various techniques. It was found that the film exhibited good high-temperature tribological properties, with the high silicon content in the inner layer providing mechanical properties and the low silicon content in the outer layer reducing friction coefficient and wear rate.
