Soft magnetic thin film, method for preparing same and magnetic head

• US 6,238,492 B1
• Filed: 10/24/1997
• Issued: 05/29/2001
• Est. Priority Date: 01/26/1989
• Status: Expired due to Fees

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Shimizu, Osamu, Yoshida, Satoshi, Katayama, Masaaki, Nakanishi, Kanji, Isomura, Tatsuya
• Primary Examiner(s): WYSZOMIERSKI, GEORGE P
• Application Number:
  US08/957,791
• Time in Patent Office: 1,313 Days
• Field of Search: 148/306, 148/310, 148/311, 148/318, 420/128
• US Class Current: 148/306
• CPC Class Codes: G11B 5/147 with cores being composed of metal sheets, i.e. laminated cores with cores composed of isolated magnetic layers, e.g. sheets in thin films G11B5/31
• CPC Class Codes: G11B 5/1878 disposed immediately adjacent to the transducing gap, e.g. "Metal-In-Gap" structure
• CPC Class Codes: G11B 5/21 the pole pieces being of ferrous sheet metal or other magnetic layers G11B5/1871 takes precedence; in thin film G11B5/31
• CPC Class Codes: G11B 5/31 using thin films G11B5/1274, G11B5/1278, G11B5/1874, G11B5/1875, G11B5/33, G11B5/49 take precedence; magnetic thin film structures H01F10/00
• CPC Class Codes: G11B 5/3109 Details G11B5/3103 takes precedence
• CPC Class Codes: G11B 5/313 Disposition of layers
• CPC Class Codes: G11B 5/3186 parallel to the gap plane, e.g. "vertical head structure"
• CPC Class Codes: H01F 1/15308 based on Fe/Ni H01F1/15325 takes precedence
• CPC Class Codes: H01F 10/131 containing iron or nickel
• CPC Class Codes: H01F 10/147 with lattice under strain, e.g. expanded by interstitial nitrogen H01F10/26 - H01F10/30 take precedence
• CPC Class Codes: H01F 10/187 Amorphous compounds H01F10/3204 takes precedence
• CPC Class Codes: H01F 10/265 Magnetic multilayers non exchange-coupled H01F10/32 takes precedence

Abstract

A soft magnetic thin micro-crystalline film of Fe_aT_bN_c (at %) wherein T is at least one of Zr, Hf, Ti, Nb, Ta, V, Mo, and W and 0<b≦20, and 0<c≦22 except the range of b≦7.5 and c≦5, shows low coercivity Hc of 80-400 Am⁻¹ (1-5 Oe) which is stable upon heating at elevated temperatures for glass bonding. This film is produced by crystallizing an amorphous alloy film of the similar composition at 350-650° C. to a crystal grain size up to 30 nm to provide uniaxial anisotropy and increased magnetic permeability at a higher frequency. It can also provide low magnetostriction around λs=0. A composite magnetic head is made using this thin film. A diffusion preventive SiO₂ layer is disposed between ferrite cores, and this thin film in the magnetic head prevents an interdiffusion layer and suppresses beat in the output signal.

Claims

1. A soft magnetic thin film comprised of a single-layer structure of a substantially uniform composition represented by the compositional formula Fe_a-mM_mT_bN_c, wherein a, b, c and m are atomic percent, M stands for at least one selected from the group consisting of Co, Ru and Cr, and T stands for at least one selected from the group consisting of Zr, Hf, Ti, Mo, and W, and wherein 0<

m/a<

0.1, 0<

b≦

20 and 0<

c≦

22 with the exclusion of the range wherein both b≦

7.5 and c≦

5, said soft magnetic thin film exhibiting a coercivity H_c of 400 Am<sup>−

1</sup> (5 Oe) or less, having a crystallographic orientation that is predominantly α

Fe(110) and having a saturation magnetostriction constant λ

s in the range from 1.6×

10<sup>−

6</sup> to 0 in an absolute value.

2. A soft magnetic thin film according to claim 1, wherein Fe is less than 85 atomic %.

3. A soft magnetic thin film according to claim 1, which has a saturation magnetostriction constant λ

s in the range from 1.4×

10<sup>−

6</sup> to 0 in an absolute value.

4. A soft magnetic thin film according to claim 1, wherein 69≦

a≦

93, 2≦

b≦

15 and 5.5≦

c≦

22.

5. A soft magnetic thin film according to claim 1, wherein the composition is within the range defined by a line interconnecting points P(91, 2, 7), Q(93, 2, 5), R(88, 7, 5), S(73, 12, 15), T(69, 12, 19), U(69, 9, 22) and V(76, 5, 19) in a pseudo ternary composition coordinate system (Fe+M, T, N).

6. A soft magnetic thin film according to claim 1, wherein the composition is within the range defined by a line interconnecting points W(88, 3.6, 8.4), X(88, 4.56, 7.44), Y(77, 8.74, 14.26) and Z(77, 6.9, 16.1) in a pseudo ternary composition coordinate system (Fe+M, T, N).

7. A soft magnetic thin film according to claim 1, wherein the soft magnetic film comprises microcrystalline grains having a size of 30 nm or less.

8. A soft magnetic thin film comprised of a single-layer structure of a substantially uniform composition represented by the compositional formula Fe_a-mM_mT_bN_c, wherein a, b, c and m are atomic percent, M stands for at least one selected from the group consisting of Co, Ru, Cr, V, Ni, Mn, Pd, Ir and Pt, and T stands for at least one selected from the group consisting of Zr, Hf, Ti, Mo and W, and wherein O<

m/a<

0.3, 0<

b≦

20 and 0<

c≦

22 with the exclusion of the range wherein both b≦

7.5 and c≦

5, said soft magnetic thin film exhibiting a coercivity H_c of 400 Am<sub>−

1</sub> (5 Oe) or less, having a crystallographic orientation that is predominantly α

Fe(110) and having a saturation magnetostriction constant λ

s in the range 1.6×

10<sup>−

6</sup> to 0 in an absolute value, provided that in the case where V is selected as M, one of b and c is in the range O<

b<

0.5 and 0<

c<

0.5, respectively.

9. A soft magnetic thin film according to claim 8 wherein Fe is less than 85 atomic %.

10. A soft magnetic thin film according to claim 8 which has a saturation magnetostriction constant λ

s in the range from 1.4×

10<sup>−

6</sup> to 0 in an absolute value.

11. A soft magnetic thin film according to claim 8, wherein the composition is within the range of 69≦

a≦

93, 2≦

b≦

15 and 5.5≦

c≦

22.

12. A soft magnetic thin film according to claim 8, wherein the composition is within the range defined by a line interconnecting points P(91, 2, 7), Q(93, 2, 5), R(88, 7, 5), S(73, 12, 15), T(69, 12, 19), U(69, 9, 22) and V(76, 5, 19) in a pseudo ternary composition coordinate system (Fe+M, T, N).

13. A soft magnetic thin film according to claim 8 wherein 0.1≦

m/a<

0.3.

14. A soft magnetic thin film according to claim 8, wherein the composition is within the range defined by a line interconnecting points W(88, 3.6, 8.4), X(88, 4.56, 7.44), Y(77, 8.74, 14.26) and Z(77, 6.9, 16.1) in a pseudo ternary composition coordinate system (Fe+M, T, N).

15. A soft magnetic thin film according to claim 8, wherein the soft magnetic film comprises microcrystalline grains having a size of 30 nm or less.

16. A soft magnetic thin film according to claim 8, which has an electric resistivity ρ

of 100 μ

Ω

cm or more.

17. A soft magnetic thin film according to claim 8, which has a saturation magnetic flux density of 10 kG or more.

18. A soft magnetic thin film according to claim 8, which has a saturation magnetic flux density of 12 kG or more.

19. A soft magnetic thin film according to claim 8, which has a saturation magnetostriction constant λ

s in the range 9×

10<sup>−

7</sup> to 0 in an absolute value.

20. A soft magnetic thin film according to claim 8, which has a saturation magnetostriction constant λ

s in the range 6×

10<sup>−

7</sup> to 0 in an absolute value.

21. A soft magnetic thin film according to claim 8, which has a saturation magnetostriction constant λ

s of from 2×

10<sup>−

7</sup> to 0 in an absolute value.

22. A soft magnetic thin film according to claim 8, which has an anisotropic field Hk of 4 Oe or more.

23. A soft magnetic thin film according to claim 8, which has a coercivity H_c of 120 Am⁻

1 (1.5 Oe) or less.

24. A soft magnetic thin film according to claim 8, which has a coercivity H_c of 80 Am⁻

1 (1.0 Oe) or less.