| 講演抄録/キーワード |
| 講演名 |
2009-07-16 14:40
データストレージ用磁気テープの熱安定性 ○西尾博明・山元 洋(明大) MR2009-16 |
| 抄録 |
(和) |
平均体積(Vphy)が小さい(約2000-5000 nm3)針状メタル(MP)および六板状Ba-ferrite(BF)粒子を用いたデータストレージ用磁気テープに関して,残留磁化(Mr)で規格化した磁化の時間(t)減衰{dM/(Mr*log t)} の減磁界依存性および保磁力(Hc)に対する揺らぎ磁界(Hf)の比とHcの温度係数{a(Hc)}との関係を検討した.MPテープに関しては,粒子の配向度(OR)がdM/(Mr*log t)および活性化体積(Vact)に及ぼす影響も調べた.Vphyが特に小さいMPおよび実験に用いた全てのBFテープのHf値は,減磁界の大きさによって大きく変化する.Vphyが同じ場合,BFテープのdM/(Mr*log t)およびHfはMPに比べて特に大きい.いずれの磁気テープもVphyが小さくなるほどdM/(Mr*log t)が増大し,熱安定性上重要なa(Hc)はHf/Hcの増加と共に大きくなる.Vphyが大きいMPテープでは,dM/(Mr*log t)はORの向上に従い低減するが,Vphyが小さい場合は不可逆磁化率の低減が難しいため,ORの改善による効果は少ない.超常磁性微粒子(約700 nm3)の存在が影響していると思われる.低減磁界における Vphy値とは無関係に,ORの改善に従い媒体ノイズに比例するVactは小さくなる.Vphyが特に小さなMPおよびBFテープのdM/(Mr*log t)を減少させるためには,Hfを低減させる考案および異方性磁界とその分布の影響を受けるHcを向上させることが重要である. |
| (英) |
The reverse field dependence of the normalized magnetization decay and the effect of the ratio of the fluctuation field (Hf) to coercivity (Hc) on the temperature coefficient of coercivity {α(Hc)} were studied for advanced data storage tapes prepared from ultrafine acicular metal particulate (MP) composite and hexagonal platelet Ba-ferrite (BF) particles. The mean volume of particles (Vphy) for these tapes varied from approximately 2000-5000 nm3. The effects of the degree of particle orientation (OR) on the normalized magnetization decay and activation volume (Vact) were also studied for advanced MP tapes. The values of Hf were not constant, but were largely dependent on the reverse field for ultrafine MP and all of BF tapes. In comparison to MP and BF tapes with approximately same Vphy, the normalized magnetization decay and Hf of BF tapes were much larger than that of MP tapes. The smaller the Vphy was, the larger the normalized magnetization decay became. The value of α(Hc), which is important for the thermal stability of high-density recording media, increased as the ratio Hf/Hc increased for both tapes. In MP tape with a larger Vphy (5300 nm3), increasing the OR was found to decrease the normalized magnetization decay. However, OR values had little effect on the normalized magnetization decay of advanced MP tape with a smaller Vphy (1700 nm3) and it was difficult to decrease the irreversible susceptibility that is affected significantly the normalized magnetization decay. These may be attributed to the existence of a few particles approaching the theoretical superparamagnetic limit. The value of Vact in the low reverse field, which is a major factor affecting media noise, decreased as OR increased regardless of Vphy. To decrease the normalized magnetization decay, it is particularly important to originate in decreasing Hf and increase Hc that related to the anisotropy field and distribution for advanced MP and BF tapes with very small Vphy. |
| キーワード |
(和) |
活性化体積 / Ba-ferrite微粒子 / データストレージ用テープ / 揺らぎ磁界 / メタル微粒子 / 熱安定性 / / |
| (英) |
Activation Volume / Ba-ferrite Particle / Data Storage Tape / Fluctuation Field / Metal Particle / Thermal Stability / / |
| 文献情報 |
信学技報, vol. 109, 2009年7月. |
| 資料番号 |
|
| 発行日 |
2009-07-09 (MR) |
| ISSN |
Print edition: ISSN 0913-5685 Online edition: ISSN 2432-6380 |
著作権に ついて |
技術研究報告に掲載された論文の著作権は電子情報通信学会に帰属します.(許諾番号:10GA0019/12GB0052/13GB0056/17GB0034/18GB0034) |
| PDFダウンロード |
MR2009-16 |