Presentation	2015-06-04 First principles study for the effect of spin fluctuation on the crystalline magnetic anisotropy in L10-type ordered alloys Naofumi Kobayashi, Kazushige Hyodo, Akimasa Sakuma,
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Abstract(in Japanese)	(See Japanese page)
Abstract(in English)	For the application of high-density magnetic devices, thermal stability of magnetization in materials is one of the key factors. In this study, we investigated the influence of the spin fluctuation at finite temperature on the uniaxial magnetic anisotropy constant ($K_{rm u}$) on $rm L1_0$-type ordered alloys, such as FePt and CoPt. In our calculation, we restricted directions of the magnetic moment in each site to two directions, and the thermal spin fluctuation was expressed as the random substitution ratio $X$ in (Fe$_{uparrow}$)$_{1-X}$(Fe$_{uparrow}$)$_{1-X}$Pt. We employed the tight-binding linear muffin-tin orbital (TB-LMTO) method within the local spin density functional theory.The disordered magnetization was taken into account by using coherent potential approximation (CPA). The result showed the relationship between $K_{rm u}$ and $$ as a function of $X$. We found that $K_{rm u}$ is proportional to n-th power of $$($napprox2$) in both FePt and CoPt. This trend is similar to that of the experimental result. We conclude that the behavior of $K_{rm u}$ of these alloys at finite temperature is well explained by a simple assumption of the Ising type fluctuation for the thermal excitation.
Keyword(in Japanese)	(See Japanese page)
Keyword(in English)	Crystalline magnetic anisotropy / First-principles calculation
Paper #	MR2015-3
Date of Issue	2015-05-28 (MR)

Conference Information
Committee	MR / ITE-MMS
Conference Date	2015/6/4(2days)
Place (in Japanese)	(See Japanese page)
Place (in English)	Tohoku Univ.
Topics (in Japanese)	(See Japanese page)
Topics (in English)	Recording Systems, etc.
Chair	Masukazu Igarashi(*) / Eiichi Miyashita(NHK)
Vice Chair
Secretary	(Syowa Denko) / (Toshiba)
Assistant	Fumiko Akagi(Kogakuin Univ.) / Takayuki Shima(AIST)

Paper Information
Registration To	Technical Committee on Magnetic Recording / Technical Group on Multi-media Storage
Language	JPN
Title (in Japanese)	(See Japanese page)
Sub Title (in Japanese)	(See Japanese page)
Title (in English)	First principles study for the effect of spin fluctuation on the crystalline magnetic anisotropy in L10-type ordered alloys
Sub Title (in English)
Keyword(1)	Crystalline magnetic anisotropy
Keyword(2)	First-principles calculation
1st Author's Name	Naofumi Kobayashi
1st Author's Affiliation	Tohoku University(Tohoku Univ.)
2nd Author's Name	Kazushige Hyodo
2nd Author's Affiliation	Tohoku University(Tohoku Univ.)
3rd Author's Name	Akimasa Sakuma
3rd Author's Affiliation	Tohoku University(Tohoku Univ.)
Date	2015-06-04
Paper #	MR2015-3
Volume (vol)	vol.115
Number (no)	MR-71
Page	pp.pp.13-16(MR),
#Pages	4
Date of Issue	2015-05-28 (MR)