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МАГНИТНАТА АНИЗОТРОПИЯ и прочия... ( ПРИЛОЖЕН МАГНЕТИЗЪМ) PowerPoint PPT Presentation


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МАГНИТНАТА АНИЗОТРОПИЯ и прочия... ( ПРИЛОЖЕН МАГНЕТИЗЪМ). Доц. д-р Михаил Михов Физически факултет на СУ “Св. Кл. Охридски” Юни, 2011 г. http://elearning-phys.uni-sofia.bg/~mikhov. Основната магнитна величина магнитен момент - M. Постоянен магнит. Постоянен магнит.

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МАГНИТНАТА АНИЗОТРОПИЯ и прочия... ( ПРИЛОЖЕН МАГНЕТИЗЪМ)

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...( )

. -

. .

, 2011 .

http://elearning-phys.uni-sofia.bg/~mikhov


-M

- I

. -

. -B

. -


,

Fe, Co, Ni, Gd,

MnAs, MnAl, Fe-, SmCo5, Nd2Fe14B, ..,

Fe3O4, CoFe2O4, BaFe12O19, ..,

....


-- -

- Hc


30109US$


8

!


-

,

:

3d- Cr, Mn, Fe, Co, Ni, 2 5 B

4f- Nd, Pr, Dy, Gd, Ho, Tb, 2 10 B


-


()

- Wex

,, ,C:

< C, Wex > kBT.

>C, kBT>Wex

.


!!

!!

...


,

  • ;

  • ;

  • ;

  • ;

  • ;

  • ;

  • ...



:

()

( .)


, -,

()

c


-

[100], [010],[001]-


Ni

-

<111>-


.


!


Wa = Kusin2


Wa - .


-; .


1.

-

( )

2.

( )


-

, .

Wso ~ -Hl.s

!


-


d- .


.

NaCl


.

3d- .


.

3d- .


  • ( -) ;

  • ;

  • ;

  • , ( -) - ;

  • , , - !


  • :

  • ;

  • ;

  • ;

  • !


-

WH = -M.H

T= H

(T )

H = f(M, r)


<

.


( , HD)


( , HD)

. , Hi,

-

, H.

HD


( , HD)

HD


WH = -i.Hi

WDa< WD


WDc< WDa






,


  • :

    • , Wex,

    • , Wa,

    • , HD,

    • , WH,

    • , Wstr,

  • .


!



( )

A ~ Wex


( )

A K :

  • (),

  • ,

  • ,

  • .

    .


( )



-Fe2O3, () .


(Alnico: Fe-Co-Ni-Al)

Hc 270 kA/m (3400 Oe)

(BH)max 30 kJ/m3

Fe-Co


() (GMR)


T .. t-t

,

,

.


T t t' = -t

T:t t' = -t

t'= - t

v' = - v

l'= - l

' = -


T t t' = -t

T:t t' = -t

t'= - t

I'= -I

H' = -H


, .

T t t' = -t

=

WH = ()-i.Hj

(i j)


T t t' = -t

, .


-


.


200 Gbpsi.

2010 . Western Digital Corp. 3 Tbit .


:

20 m

. .



Co-Pt-Cr

GMR

.

Nd2Fe14B ,

Nd2Fe14B -


Nd2Fe14B


, .

,

- :


!


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