CVDU ê s0 n É® Žz º Pt/TiO 2 /SiO 2 /Si M “ ˜ m; c V R ËX ê sS â à ŠCrO 2 U c lT c l

CVDU ê s0 n É® Žz º Pt/TiO ₂ /SiO 2 /Si M “ ˜ m; c V R ËX ê sS  â à ŠCrO 2 U c lT c l

) í

< ø ¶ B* 9  · ƒ ç ¡) o g ` @ · ƒ ‘ š+ ä ­ £ · ' Ö <‹ È Ñ( 8  · † ç ¡* å 0 å  ·  ™ »Œ ‰ x Z 9  · ö ¶ B# Ü \ 8 ; · ‚ Ð . > 0 ï F ^∗

Â

Òí ß –@ /† < Ɠ § Ó ü t o † < Æõ , Ä »„  ^ ‰Ó ü t$ í ƒ  ½ ¨™ è,  Òí ß – 609-735 (2004¸   4 Z 4 1{ 9  ~ à Î6 £ §)

Ñ þ

˜F K_  $ í  © œ~ ½ ӆ ¾ Ós    É r ¿ º (111) Pt/TiO

2

/SiO

2

/Si ü < (200) Pt/TiO

2

/SiO

2

/Si l ó ø Í 0 A\  CVD~ ½ Ó Z O

`  ¦  6   x # Œ CrO

2

~ à Ì} Œ •`  ¦ $ í  © œr (   . (111) Pt/TiO

2

/SiO

2

/Si l ó ø Í 0 A\ " f  H (200)~ ½ ӆ ¾ ÓÜ ¼– Ð $ í



© œ % i Ü ¼ 9,   & ñ  o ¸ ú ˜  ) a  y Œ •+ þ A_    & ñ w n [ þ t s  › ' a¹ 1 Ï÷ &% 3  . (200) Pt/TiO

²

/SiO

2

/Si l ó ø Í 0 A\ 

"

f  H (110) ~ ½ ӆ ¾ Ó_  $ í  © œ`  ¦ ˜ Ð% i Ü ¼ 9, t Ô  æ — ¸€ ª œ_    & ñ w n [ þ t s  › ' a¹ 1 Ï÷ &% 3  . $ í  © œ~ ½ ӆ ¾ Ós    É r ¿ º CrO

2

~ Ã

Ì} Œ •_   l & h  : £ ¤$ í `  ¦ › ' a¹ 1 Ï l  0 A # Œ SQUIDü < MFM(magnetic force microscope)`  ¦  6   x % i  .

SQUID \  _ ô  Ç s § 4 / B G‚  õ  MFM_   l ì  r% i \ " f easy-axis ¨ î €  _  ~ ½ ӆ ¾ ÓÜ ¼– Ð
ê ø Í >  ” > r F    H

 כ

`  ¦ ˜ Ѐ Œ ¤Ü ¼ 9, MFM_   l ì  r% i \ " f ³ ð€  _  + þ A © œs    É r ¿ º ~ à Ì} Œ •s  ˜ Ðs   H  l ì  r% i \ " f_  " î € Œ ™\ 

s \  ¦  7 H_  % i  .  " é ¶F  gì  r$ 3 l \  ¦ s 6   x # Œ ~ à Ì} Œ •_  F  g† < Æ& h  : £ ¤$ í `  ¦ › ' a¹ 1 Ï % i Ü ¼ 9,   © œ\    É r F  g

„ 

• ¸• ¸\  @ /ô  Ç LSDA(local spin density approximation)\  _ K  > í ß – ÷ &# Q”    ½ ™× ¼½ ¨› ¸\  › ' aº  ô  Ç  7 H _

\  ¦ % i  .

PACS numbers: 60

Keywords: CVD~ ½ ÓZ O , CrO2, SQUID, MFM,  ½ ™× ¼½ ¨› ¸, LSDA

I. " e  ] Ø

þ

j  H „  • ¸ „   _  Û ¼— 2 ;  Ä »• ¸\  ¦ s 6   x   H Û ¼— 2 ;à Ԗ Ð _ ”

Û ¼\  ¦ s 6   xô  Ç  © œq _  > h¥ Æ \  @ /ô  Ç ; Ÿ ¤V , “ É r ƒ  ½ ¨ ”  ' Ÿ 

÷

&“ ¦ e ” Ü ¼ 9, s \    É r Z  }“ É r  l  ì  rF G`  ¦ t   H y © œ 

$ í

^ ‰ Ó ü t| 9 \  @ /ô  Ç ƒ  ½ ¨ ¢ ¸ô  Ç ´ ú §s  ”  ' Ÿ ÷ &“ ¦ e ”   [1, 2].

Ó

ü t| 9 \  @ /ô  Ç › ' a& h \ " f  H, „    î  rì ø Í  100 %  l  ì  r F

G ) a half-metallic y © œ $ í ^ ‰ Û ¼— 2 ;à Ԗ Ð_ ” Û ¼_  6 £ x6   x \ " f

´ ú

§“ É r 0 p x$ í `  ¦ ˜ Г    [3]. s    › ' a& h \ " f ^  ¦ M :, CrO

2

  H



½ ™× ¼½ ¨› ¸_  > í ß –\  _ K " f half-metallic y © œ $ í ^ ‰ H † d s

 \ V © œ÷ &% 3 Ü ¼ 9 [4], 100 %  s   l  ì  rF G ÷ &# Qe ”  



 H  כ s  spin-polarized photoemissionõ  superconduction point contact z  ´+ « >\  _ K " f ˜ Г ¦÷ &% 3   [5,6].  l  ì  rF G

 )

a „   _  : £ ¤$ í `  ¦ Û ¼— 2 ;à Ԗ Ð_ ” Û ¼\  & h 6   x l  0 A # Œ „  • ¸

$ í

s  e ”   H l ó ø Í 0 A\  CrO

2

~ à Ì} Œ •`  ¦ $ í  © œr v   H  כ s   | à Рf ”

  . Õ ª Q
, CrO

²

~ à Ì} Œ •“ É r : £ ¤& ñ ô  Ç l ó ø Í\ " fë ß – ‚  × þ ˜& h 

“

  $ í  © œ`  ¦ ˜ Г    [7]. CrO

²

\ " f Cr s “ : r[ þ t“ É r Cr

⁺⁴

(d

²

)



© œI – Ð ” > r F   9, s “ : r { © œ 2 µ

_B

_   l — ¸F ' pà Ô\  ¦
  · p



. CrO

²

  H & ñ ~ ½ Ó_  é ß –0 A± ú  ñ ß –(a = b = 4.419 ˚ A, c = 2.915

˚ A)`  ¦ t  9, U  ´>  Z þ t # Q”   í ß –™ è¼ 1 π  ^ ‰ c» ¡ ¤_  ~ ½ ӆ ¾ ÓÜ ¼– Ð 90 • ¸m ”  d  ¦ # Q”   + þ AI \  ¦ ”   À Ò 9 ½ ¨› ¸s  . Õ ª QÙ ¼– Ð, ¿ º

∗

E-mail: [email protected]

Fig. 1. Schematic diagrams of (a) (111) and (b) (200) planes of Pt.

>

h_  d „    » ¡ ¤@ ÷ &t  · ú §“ É r t

2g

Y U6 \ š\ " f F K5 Å q  © œ`  ¦ + þ A

$ í

ô  Ç . CrO

2

  H easy-axis  c» ¡ ¤ \ 
ê ø Í  9 s \  @ /ô  Ç



l s ~ ½ Ó$ í `  ¦
 ? / 9, y © œ $ í  © œ„  s  390 K\ " f { 9 

# Qè ß – .

II. ÷ m Ç] M öU ê s0 n É

CrO

2

~ à Ì} Œ •“ É r ± ú “ É r “ : r • ¸\ " f   & ñ  © œs  ï  r î ß –& ñ & h s  9



© œ· ú š_  í ß –™ è ì  r0 Al \ " f CVD ~ ½ ÓZ O \  _ K " f ¸ ú ˜ $ í  © œ

÷

&# Q”    [10]. CrO

2

~ à Ì} Œ •\   H À Ò 9 ½ ¨› ¸_  TiO

₂

,  

-535-



s # Q ¢ ¸  H TiO

2

/Si l ó ø Í[ þ t s   6   x ÷ &# Q4 R M ® o   [11, 12]. ‘ : r ƒ  ½ ¨\ " f  H CrO

2

~ à Ì} Œ •_  $ í  © œ ~ ½ ӆ ¾ Ó\    É r   l

& h  : £ ¤$ í `  ¦ › ' a¹ 1 Ï l  0 A # Œ $ í  © œ~ ½ ӆ ¾ Ós    É r ¿ º (111) Pt/TiO

2

/SiO

2

/Si ü < (200) Pt/TiO

2

/SiO

2

/Si l ó ø Í 0 A\  CVD ~ ½ ÓZ O `  ¦  6   x # Œ CrO

²

~ à Ì} Œ •`  ¦ $ í  © œr (   . Ñ þ ˜F K

“ É

r €  d ” { 9 ~ ½ Ó_  ½ ¨› ¸\  ¦ t  9 é ß –í  H{ 9 ~ ½ Ó_  é ß –0 A± ú  ñ ß –_ 

 

  © œÃ º  H 3.923 ˚ A s  . Fig. 1_  (a)ü < (b)  H Ñ þ ˜F K_  (111) ü < (200) ³ ð€  `  ¦
  · p  כ s  . (111) ³ ð€  \ " f  H y

Œ

•   _  U  ´s  2.774 ˚ A õ  4.805 ˚ A_  f ”  y Œ •+ þ A`  ¦ Ò q ty Œ •½ + É Ã

º e ” Ü ¼ 9, s  M : CrO

²

ü <_     Ô  ¦{ 9 u   H 4.8 % – Ð > í ß –

÷

&# Q”   . CrO

2

~ à Ì} Œ •“ É r (100) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œ  9, c» ¡ ¤ s  l

ó ø Í\ 
ê ø Íô  Ç ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œ| ¨ c  כ s  \ V © œ÷ &# Q”   . Õ ª



Q
, (200) ³ ð€  `  ¦ ˜ Ѐ  , CrO

₂

    \ x % 7 ˜[ >  ½ ¨› ¸– Ð

$ í

 © œ½ + É › ¸| `  ¦ ¹ 1 Ô`  ¦ à º \ O Ü ¼ 9, s – РÒ'  CrO

2

~ à Ì} Œ •_  Ä

º‚   $ í  © œë ß –s  \ V © œ÷ &# Q”   .

CrO

₂

~ à Ì} Œ •`  ¦ CrO

3

 Ä º 8\  ¦  6   x # Œ CVD ~ ½ ÓZ O Ü ¼

–

Ð $ í  © œr (   . Two-zone „  l – Ðü < $ 3 % ò › ' a Ü ¼– Ð s À Ò# Q

”

  CVD ì ø Í6 £ x l \  ¦  6   x % i Ü ¼ 9, l ó ø Í_  “ : r • ¸  H 410

^◦

C Õ

ªo “ ¦ CrO

3

_  “ : r • ¸  H 260

^◦

C\  ¦ Ä »t  % i  . í ß –™ è  H  © œ

Fig. 2. The x-ray patterns of the CrO

2

thin films grown on preferentially oriented (a) (111) and (b) (200) Pt/TiO

2

/SiO

2

/Si substrates.

·

ú š\ " f ì  r{ © œ 160 cc\  ¦ f  ˧ 4 Ü ¼ 9, SEMÜ ¼– Ð ¿ ºa \  ¦ 8 £ ¤& ñ K 

‘

: r   õ  6000 ˚ A`  ¦ % 3 % 3  . ~ à Ì} Œ •_  ½ ¨› ¸& h  : £ ¤$ í `  ¦ ì  r$ 3   l

 0 AK " f XRD 8 £ ¤& ñ `  ¦ % i  .  l & h  : £ ¤$ í `  ¦ › ' a¹ 1 Ï l  0 A # Œ, SQUID(superconduction quantum interference device) \  _ ô  Ç s § 4 / B G‚  `  ¦ › ' a¹ 1 Ï % i Ü ¼ 9, MFM(Seiko, SPA400)`  ¦ s 6   x # Œ ³ ð€  _  + þ A © œ\  @ /ô  Ç  l ì  r% i  — ¸

€

ª œ`  ¦ › ' a¹ 1 Ï % i  . AFM(atomic force microscope)\  _  ô 

Ç  l ì  r% i _  › ' a¹ 1 Ï\   H  ïµ 1 Ïà Ô  ïh A ) a z  ´o – B H   p 9 Y U

!

Q(Û ¼á Ôa A  © œÃ º k ∼2.1 N/m, “ ¦Ä »”  1 l x à º ω

⁰

∼32 kHz)\  ¦



6   x % i  . 8 £ ¤& ñ r  active trace mode  Ô  ¦ o   H 8 £ ¤& ñ ~ ½ Ó Z O

`  ¦  6   x % i Ü ¼ 9, s  ~ ½ ÓZ O `  ¦ ¿ º   _  8 £ ¤& ñ õ & ñ Ü ¼– Ð s  À

Ò# Q”   . ' Í   P : 8 £ ¤& ñ \ " f  H ³ ð€  _  + þ A © œë ß –`  ¦ % 3 >  ÷ &

“

¦, ¿ º   P : 8 £ ¤& ñ \ " f  H ' Í   P : 8 £ ¤& ñ \ " f % 3 # Q”   ³ ð€   _

 + þ A © œ\  @ /ô  Ç & ñ ˜ Ð\  ¦ t “ ¦ { 9 & ñ ô  Ç  o  Ä »t   ) a  © œ I

\ " f  l § 4 \  _ K    p 9 Y U! Q_  0 A © œ_     o\  ¦ { 9 6 £ § Ü

¼– Ð+ ‹  l ì  r% i \  @ /ô  Ç & ñ ˜ Ð\  ¦ % 3 >   ) a   [13]. F  g† < Æ& h  :

£

¤$ í ì  r$ 3 \ " f  H  " é ¶ì  rF  g K $ 3 l \  ¦  6   x # Œ, F  g„  • ¸• ¸

\

 @ /ô  Ç LSDA(local spin density approximation)\  @ / 

#

Œ  7 H_  % i  .

III. + s ÇÊ Ý õ m Í À X Ø8 ý

Fig. 2_  (a)ü < (b)  H CrO

2

~ à Ì} Œ •_  XRD Á º] (`  ¦
 



· p  כ s  . Fig. 2_  (a)\  ¦ ˜ Ѐ   Fig. 1_  (a)\ " f  7 H_ ô  Ç

Fig. 3. The hysteresis loops of the (200) oriented CrO

2

thin films, (a) and (b), and the (110) oriented CrO

2

thin

films, (c) and (d). The (a) and (c) is in the case when

the applied field is parallel to the surface. The (b) and

(d) is in the case when the applied field is perpendicular

to the surface.

 כ

% ƒ! 3     Ô  ¦ u  4.3 %s “ ¦ c» ¡ ¤ s  l ó ø Í_  ¨ î €  \ 
 ê

ø Íô  Ç CrO

₂

~ à Ì} Œ •_  (200)õ  (400) 4 Ÿ x Ä ºo  › ' a¹ 1 Ï÷ & 9,  

 

& ñ | 9 _  (111) Pt l ó ø Í 0 A\  $ í  © œ % i Ü ¼Ù ¼– Ð CrO

²

~ Ã Ì }

Œ • ¢ ¸ô  Ç \ x % 7 ˜[ >  t  · ú §“ ¦    & ñ ~ à Ì} Œ •Ü ¼– Ð (100) ~ ½ ӆ ¾ Ó _  Ä º‚   $ í  © œs  { © œƒ    . Fig. 2_  (b)\  ¦ ˜ Ѐ   CrO

2

~ Ã Ì }

Œ •s  (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð Ä º‚   $ í  © œô  Ç  כ `  ¦ · ú ˜ à º e ”  . ¿ º ~ Ã Ì }

Œ

•_   â Ä º ¨ î €  \  @ /ô  Ç     © œÃ º  H q 5 p wô  Ç ° ú כ`  ¦ ”   .

 

& ñ _  $ í  © œ~ ½ ӆ ¾ Ó\  @ /ô  Ç  l & h  : £ ¤$ í `  ¦ Ò q ty Œ • €  , ¿ º ~ Ã Ì }

Œ • — ¸¿ º easy-axis l ó ø Í_  ¨ î €  \ 
ê ø Íô  Ç ~ ½ ӆ ¾ Ó\  e ”  



 H  כ `  ¦ CrO

2


 ? /  H easy-axis  c» ¡ ¤ \  e ”    H  כ

\

" f \ V © œ½ + É Ã º e ”  .

Fig. 3“ É r SQUID \  _ K  % 3 # Q”   2 × 2 mm

²

_  ß ¼l _  CrO

₂

~ à Ì} Œ •[ þ t_  y © œ $ í s § 4 / B G‚  `  ¦
  · p  כ s  . s § 4  /

B

G‚  [ þ t“ É r CrO

2

~ à Ì} Œ •[ þ t_  easy-axia l ó ø Í_  ¨ î €  \ 
 ê

ø Í >  e ”    H  כ `  ¦
 ? /“ ¦ e ”  . Fig. 3_  (a)ü < (b)  H



l  © œ`  ¦ l ó ø Í\ 
ê ø Íô  Ç ~ ½ ӆ ¾ ÓÜ ¼– Ð “   % i `  ¦ M :_  y © œ 

Fig. 4. (a) AFM and (b) MFM images of the (200) ori- ented CrO

2

thin films. (c) schematic figure of the po- sition of the cantilever’s tip on the tetragonally shaped grain with a fixed trace distance and the in-plane ori- ented magnetic flux during MFM scanning.

$ í

s § 4 / B G‚  `  ¦
  · p  כ s  9, „  + þ A& h “   y © œ $ í ^ ‰ ~ à Ì} Œ • _  s § 4 / B G‚   + þ AI \  ¦
 ? /“ ¦ e ”  . Õ ª Q
, 
_   l  ì

 r% i \  _ ô  Ç „  + þ A& h “   y © œ $ í s § 4 / B G‚  õ   H  Ø Ô 9, s 



 H hard axis_  l # Œ\  _ ô  Ç    & ñ CrO

₂

~ à Ì} Œ •_  : £ ¤$ í

\

 _ ô  Ç  כ s  . (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º ï ß –À ӗ ¸F ' p à

Ô(∼3.2 × 10

⁻⁴

emu)  (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º_  ï

ß –À ӗ ¸F ' pà Ô(∼1.4 × 10

⁻⁴

emu) ˜ Ð  ß ¼ 9, ì ø ̀  \  Ÿ í o— ¸ F '

pà ԍ  H y Œ •y Œ • ∼7.5 × 10

⁻⁴

ü < ∼2.5 × 10

⁻⁴

s  . (200) ~ ½ Ó

†

¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º ™ è  © œ(∼64 Oe)_  ß ¼l   H (110) ~ ½ Ó

†

¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º_  ™ è  © œ(∼360 Oe)˜ Ð   Œ • . Fig.

3_  (c)ü < (d)  H  l  © œ`  ¦ l ó ø Í\  à ºf ” ô  Ç ~ ½ ӆ ¾ ÓÜ ¼– Ð “  

% i `  ¦ M :_  s § 4 / B G‚  `  ¦
  · p  כ s  9, easy-axis\  à º f ”

Ü ¼– Ð  l  © œs  “  ÷ &% 3 l  M :ë  H s  . (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð

$ í

 © œô  Ç  â Ä º ï ß –À ӗ ¸F ' pà Ô(∼9.0 × 10

⁻⁵

emu)  (200) ~ ½ ӆ ¾ Ó Ü

¼– Ð $ í  © œô  Ç  â Ä º_  ï ß –À ӗ ¸F ' pà Ô(∼4.5 × 10

⁻⁵

emu) ˜ Ð  ß

¼ 9, (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º ™ è  © œ(∼240 Oe)_  ß ¼

Fig. 5. The (a) AFM and (b) MFM images of the (110)

oriented CrO

2

thin films. (c) schematic figure of the

position of the cantilever’s tip on the inclined grain with

a fixed trace distance and the in-plane oriented magnetic

flux during MFM scanning.

l

  H (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º_  ™ è  © œ(∼280 Oe)˜ Ð



  Œ • . (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º_  CrO

2

~ à Ì} Œ •_    l

 s ~ ½ Ó$ í s  (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç  â Ä º˜ Ð  ß ¼ . Õ ª



Q
, s  כ `  ¦ XRD \  _ ô  Ç easy-axis ¨ î €   © œ\  e ”    H

 כ

Ü ¼– РÒ'  SQUID\  _ ô  Ç s § 4 / B G‚  _  s \  ¦ [ O " î  l

  H # Q§ >  .

SQUID \ " f % 3 “ É r  « Ñ_  s \  ¦ › ¸  l  0 A # Œ, $ í



© œ~ ½ ӆ ¾ Ós    É r ¿ º CrO

2

~ à Ì} Œ •[ þ t \  @ / # Œ AFMü < MFM

`

 ¦ 8 £ ¤& ñ % i  . Fig. 4_  (a)  H (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ à Ì} Œ •_  AFM + þ A © œ`  ¦
  · p  כ s  .   & ñ  o ¸ ú ˜

 )

a  y Œ •+ þ A_   H   & ñ w n [ þ t s  › ' a¹ 1 Ï÷ & 9, y Œ •   & ñ w n [ þ t_  ~ ½ Ó

†

¾ Ós  Ô  ¦ ½ ©g Ë :& h “    כ “ É r    & ñ Pt_  % ò † ¾ ÓÜ ¼– Ð    & ñ $ í



© œ % i 6 £ §`  ¦ · ú ˜ à º e ”  . Fig. 4_  (b)  H (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð

$ í

 © œô  Ç CrO

2

~ à Ì} Œ •_  MFM + þ A © œ`  ¦
  · p  כ s  . AFM õ

 MFM\  S X ‰ @ /  ) a  Òì  r`  ¦ ˜ Ѐ  , AFM  H + þ A © œ\ " f  H ˜ Ð

€ 

   & ñ w n _   â >  ˜ Ѐ     É r l Ö  ¦ l \  ¦ t   H  כ \ 

@

/ # Œ, MFM\ " f  H  © œ_     o  Ò× ¼ Qî  r  כ `  ¦ · ú ˜ à º e ”

 . s  כ “ É r Fig. 4_  (c)\ " f
  · p   & ñ w n  — ¸€ ª œ\  @ / ô 

Ç  כ Ü ¼– Ð [ O " î ½ + É Ã º e ”  .  l  ì  rF G_  ~ ½ ӆ ¾ Ós  ¨ î €  \  Z

 ~“    © œI \ " f   & ñ w n _   â > \ " f ì  rF G_  l Ö  ¦ l  / å L

 

½ + É M :  H MFM tip õ  ~ à Ì} Œ •_  ì  rF G s  " f– Ð Ã ºf ” Ü ¼– Ð ÷ &

“

¦, tips  f ” ] X & h “    l  ì  rF G_     o\  ¦ % 3 `  ¦ à º \ O >  ÷ &

#

Q, MFM\ " f  © œ_     o  Ò× ¼X O > 
 è ß – .

Fig. 5_  (a)  H (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ à Ì} Œ •_  AFM + þ A © œ`  ¦
  · p  כ s  . t Ô  æ — ¸€ ª œ_    & ñ w n [ þ t s  › ' a

¹

1 Ï÷ & 9, y Œ •   & ñ w n [ þ t_  ~ ½ ӆ ¾ Ós  Ô  ¦ ½ ©g Ë :& h “    כ “ É r    

&

ñ Pt_  % ò † ¾ ÓÜ ¼– Ð CrO

²

   & ñ s  $ í  © œ % i l  M :ë  H s 



. Fig. 5_  (b)  H (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ à Ì} Œ •_  MFM + þ A © œ`  ¦
  · p  כ s  . AFMõ  MFM\  S X ‰ @ /  ) a Â Ò ì

 r`  ¦ ˜ Ѐ  , AFM + þ A © œ\ " f  H   & ñ w n _   â >  q Û ¼1 p uô  Ç l

Ö  ¦ l \  ¦ t   H  כ \  @ / # Œ, MFM\ " f phase_     o

 / å L  ô  Ç  כ `  ¦ · ú ˜ à º e ”  . s  כ “ É r Fig. 5_  (c)\ " f
 

 · p   & ñ w n  — ¸€ ª œ\  @ /ô  Ç  כ Ü ¼– Ð [ O " î ½ + É Ã º e ”  .  l  ì

 rF G_  ~ ½ ӆ ¾ Ós  ¨ î €  \  Z  ~“    © œI \ " f   & ñ w n _   â > \ 

"

f l Ö  ¦ l  q Û ¼1 p u ½ + É M :  H MFM_  tip\  e ”   H  l  ì  r F

G_  ~ ½ ӆ ¾ Ó\  @ / # Œ à ºf ” Ü ¼– Ð ÷ &# Q e ” t ë ß – ³ ð€  \  tips  f ”

] X  ] X   H½ + É Ã º e ” “ ¦, tips   l  ì  rF G_     o\  ¦ f ” ] X  % 3 

`

 ¦ à º e ” >  ÷ &# Q, MFM\ " f  © œ_     o / å L   > 
  è

ß – .

Fig. 6_  (a)ü < (b)  H  " é ¶ì  rF  g K $ 3 l \  _ ô  Ç F  g„  • ¸

•

¸ü < LSDA\  _ K  > í ß –÷ &# Q”   \  -t  • ¸³ ð\  ¦
  · p  כ s

 . Fig. 6_  (a)\ " f (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ Ã Ì }

Œ

•_  F  g„  • ¸• ¸ (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ à Ì} Œ •_  F  g

„ 

• ¸• ¸˜ Ð  ß ¼> 
 
 9, s   H   & ñ  o\  _ ô  Ç   õ – Ð Ò q

ty Œ •÷ &# Q ”   . $ í  © œ~ ½ ӆ ¾ Ó\    É r F  g„  • ¸• ¸_  s   H \ O 

Fig. 6. (a) The optical conductivity of CrO2 thin films and (b) the density of states of CrO2 obtaind from the reference 14.

%

3 Ü ¼ 9, ± ú “ É r \  -t \ " f  H Drude + þ AI _  F K5 Å q& h “   : £ ¤ f ç

`  ¦
 ? /“ ¦ e ”  . Fig. 6(b)_  LSDA\  @ /ô  Ç CrO

₂

_ 

\

 -t  • ¸³ ð\ " f F  g„  • ¸• ¸ 4 Ÿ x Ä ºo  0 Au \  @ / # Œ Ò q ty Œ •

½ +

É Ã º e ”  . 2 eVü < 3.4 eV   H % ƒ\  4 Ÿ x Ä ºo  › ' a¹ 1 Ï÷ &  H  כ

“

É r Fermi \  -t   – Ð  A \ " f 2 eV ÷ &  H / B M Ü ¼– Ð   Ã

ºÛ ¼— 2 ;_  „   ü < ™ èà ºÛ ¼— 2 ;_  „    `  …  " f F  g„  • ¸• ¸

\

 l # Œ   H  כ \  l “  ô  Ç  [14].

IV. + s Ç Â ] Ø

CVD ~ ½ ÓZ O `  ¦  6   x # Œ (111) Pt/TiO

2

/SiO

₂

/Si l  ó

ø Í 0 A\ " f  H (200)~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ à Ì} Œ •õ , (200) Pt/TiO

2

/SiO

2

/Si l ó ø Í 0 A\ " f  H (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

₂

~ à Ì} Œ •`  ¦ % 3 % 3  . SQUIDü < XRD_  z  ´+ « >Ü ¼– Ð ~ à Ì} Œ •

 

& ñ _  easy-axis ¨ î €  \ 
ê ø Í    H  כ `  ¦ z ´ »~ à Îg Ë >½ + É Ã º e ”

% 3  . AFMõ  MFM 8 £ ¤& ñ   õ – РÒ' ,   & ñ w n _  — ¸€ ª œ

\

      É r SQUID 8 £ ¤& ñ   õ \  ¦ ˜ Ð ¢ - a [ O " î ½ + É · ú ˜ à º e ” 

%

3  . (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ à Ì} Œ •\ " f  H  y Œ •+ þ A_ 

 

& ñ w n [ þ t s  › ' a¹ 1 Ï÷ &% 3 “ ¦, (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

₂

~ Ã Ì }

Œ •\ " f  H t Ô  æ — ¸€ ª œ_    & ñ w n [ þ t s  › ' a¹ 1 Ï÷ &% 3  . MFM 8 £ ¤

&

ñ Ü ¼– РÒ' , ~ à Ì} Œ •[ þ t_    & ñ w n  — ¸€ ª œ\    É r ì  r$ 3 `  ¦ ½ + É Ã º e ”

% 3  .   & ñ w n _  l Ö  ¦ l    É r / B M_  MFM_   © œ   o



 H tip s  f ” ] X & h “    5 Å q_     o\  ¦ Ö ¼‚  ´ à º \ O l  M :ë  H \  Â

Ò× ¼ Qî  r    o\  ¦
 ? /% 3 Ü ¼ 9,   & ñ w n _  l Ö  ¦ l  q  Û

¼1 p uô  Ç / B M \ " f_   © œ   o  H tip s  f ” ] X & h “    5 Å q_     o

\

 ¦ Ö ¼‚  ´ à º e ” l  M :ë  H \  / å L  ô  Ç    o\  ¦ ˜ Г   .  " é ¶ì  r F 

g K $ 3 l \  _ ô  Ç F  g„  • ¸• ¸_  ì  r$ 3 \ " f (200) ~ ½ ӆ ¾ ÓÜ ¼– Ð

$ í

 © œô  Ç CrO

₂

~ à Ì} Œ •_  F  g„  • ¸• ¸ (110) ~ ½ ӆ ¾ ÓÜ ¼– Ð $ í  © œô  Ç CrO

2

~ à Ì} Œ •_  F  g„  • ¸• ¸˜ Ð  ß ¼> 
 
 9, s   H   & ñ  o

\

 _ ô  Ç   õ – Ð Ò q ty Œ •÷ &# Q”   . $ í  © œ~ ½ ӆ ¾ Ó\    É r F  g„  • ¸

•

¸_  s   H \ O % 3 Ü ¼ 9, ± ú “ É r \  -t \ " f  H Drude + þ AI  _

 F K5 Å q& h “   : £ ¤f ç `  ¦
 ? /% i  .

P c

p 8 ý ò k >

This work was supported by Research fund from Pusan National University.

Y c

p w Š à U Ø ”  ô

[1] A. Gupta, X. W. Li and Gang Xiao, Appl. Phys.

Lett. 78, 1894 (2001); J. Rudolph, H. M. Gibbs, G.

Khitrova and M. Oestreich, 82, 4516 (2003); Qing- feng Sun, Hong Guo and Jian Wang, Phys. Rev.

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Half-Metallic CrO ₂ Thin Films on Pt/TiO ₂ /SiO ₂ /Si Substrates by Chemical Vapor Deposition

J. Y. Son, S. H. Bang, J. W. Park, H. B. Moon, Y. H. Jang, K. H. Kim, K. S. Song and J. H. Cho

^∗

RCDAMP and Department of Physics, Pusan National University, Busan 609-735

(Received 1 April 2004)

We report differences in the growth mechanisms of half-metallic CrO

2

thin films deposited on preferentially oriented (111) and (200) Pt/TiO

2

/SiO

2

/Si substrates by using chemical vapor deposi- tion method. The CrO

2

thin films grown on (111) Pt/TiO

2

/SiO

2

/Si substrates were (200) oriented and had crystalline rectangular grains. On the other hand, for (200) Pt/TiO

2

/SiO

2

/Si substrates, the CrO

2

thin films were (110) oriented and had wedge-shaped grains. The ferromagnetic domains of the CrO

2

thin films were observed with a magnetic force microscope at room temperature and the orientational dependence of the magnetization was observed using a SQUID magnetometer.

While the ferromagnetic domains of both films showed an in-plane ferromagnetic easy-axis, result- ing from shape anisotropy, and orientation of the easy-axis along the in-plane film direction at the domain boundaries, the magnetic domains showed marked contrast difference at domain boundaries resulting from the different surface topographies. Ellipsometery measurements were performed on the CrO

2

thin films, and the optical conductivity was obtained from the ellipsometry data. The dependence of the optical conductivity on the photon energy was compared with the band structure calculated using the local spin density approximation.

PACS numbers: 60

Keywords: CVD, CrO2, SQUID, MFM, Band structrue, LSDA

∗

E-mail: [email protected]