US5510172A
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Magnetic multilayer film and magnetoresistance element
Assignee: TDK Corp
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Filing: 1993-06-23
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Granted: 1996-04-23
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Expires: 2013-06-23
Abstract
Abstract A magnetic multilayer film having magnetoresistance (MR) is prepared by depositing at least two magnetic thin films having different coercive forces while interposing a non-magnetic thin film therebetween. A first magnetic thin film having a lower coercive force has a squareness ratio SQ1 and a thickness t1, a second magnetic thin film having a higher coercive force has a squareness ratio SQ2 and a thickness t2, and the non-magnetic thin film has a thickness t3. A first form of the invention requires 4 ANGSTROM </=t2<30 ANGSTROM , 20 ANGSTROM <t1</=200 ANGSTROM , t1>t2, t3</=200 ANGSTROM , 0.7</=SQ1</=1.0, and 0.1</=SQ2</=0.8, thereby achieving a magnetic multilayer film which shows a great MR ratio of several percents under an external magnetic field of several Oe, an excellent rise across zero magnetic field and heat resistance. A second form of the invention requires 4 ANGSTROM <t2<20 ANGSTROM , 5 ANGSTROM <t1</=20 ANGSTROM , t1<t2 and 32 ANGSTROM <t3<50 ANGSTROM , thereby achieving a magnetic multilayer film which is increased in MR ratio, MR slope between -50 Oe and +50 Oe, and high-frequency MR slope while showing minimized hysteresis. There are obtained MR elements, typically high sensitivity MR sensors and MR heads capable of high density magnetic recording.
Inventors
- 👤 Satoru Araki
- 👤 Daisuke Miyauchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:07
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/06; G01R33/09; G01R33/093; B; B82; B82Y; B82Y10/00; B82Y25/00; B82Y40/00; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; H; H01; H01F; H01F10/00; H01F10/32; H01F10/324; H01F10/3268; H01F10/3281; H01F41/00; H01F41/14; H01F41/30; H01F41/302; H01F41/303; H10; H10N; H10N50/00; H10N50/80; H10N50/85; G11B2005/3996; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/11; Y10T428/1107; Y10T428/1121; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
148 words
A magnetic multilayer film, comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first and second magnetic thin films have different coercive forces, said first magnetic thin film having a lower coercive force and a squareness ratio SQ 1 of from 0.7 to 1.0 and said second magnetic thin film having a higher coercive force and a squareness ratio SQ 2 of from 0.1 to 0.8; the first magnetic thin film has a thickness t 1 , the second magnetic thin film has a thickness t 2 and the non-magnetic thin film has a thickness t 3 wherein 4 Å≦t 2 <30 Å20 Å<t 1 <200 Å, t 1 >t 2 and 4 Å<t 3 <60 Å, and wherein the ratio of coercive force between adjacent magnetic thin films is 1.2:1 to 100:1.
Claim 2
Dependent Claim
148 words
A magnetic multilayer film, comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first and second magnetic thin films have different coercive forces, said first magnetic thin film having a lower coercive force and a squareness ratio SQ 1 of from 0.7 to 1.0 and said second magnetic thin film having a higher coercive force and a squareness ratio SQ 2 of from 0.1 to 0.8; the first magnetic thin film has a thickness t 1 , the second magnetic thin film has a thickness t 2 and the non-magnetic thin film has a thickness t 3 wherein 4 Å≦t 2 <30 Å20 Å<t 1 <200 Å, t 1 >t 2 and 4 Å<t 3 <60 Å, and wherein the ratio of coercive force between adjacent magnetic thin films is 1.2:1 to 100:1.
Claim 3
Dependent Claim
17 words
The magnetic multilayer film of claim 1 wherein SQ 2 /SQ 1 is from 0.3 to 1.0.
Claim 4
Dependent Claim
22 words
The magnetic multilayer film of claim 1 wherein 4 Å≦t 2 ≦28 Å, >Å≦t 1 , and t 1 ≧1.05t 2 .
Claim 5
Dependent Claim
52 words
A magnetic multilayer film as set forth in any one of claims 1 to 3, which is prepared by a method comprising the steps of: depositing the first and second magnetic thin films while interposing the non-magnetic thin film therebetween and effecting heat treatment at a temperature of up to 500° C.
Claim 6
Dependent Claim
112 words
A magnetic mulitlayer film, comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first magnetic thin film having a lower coercive force has a thickness t 1 , said second magnetic thin film having a higher coercive force has a thickness t 2 , and said non-magnetic thin film has a thickness t 3 , which fall in the range: 4 Å<t 2 <20 Å, 5 Å<t 1 ≦20 Å, t 1 >t 2 , and 32 Å<t 3 <50 Å, and wherein a ratio of coercive force between adjacent magnetic thin film is 1.2:l to 100:1.
Claim 7
Dependent Claim
112 words
A magnetic mulitlayer film, comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first magnetic thin film having a lower coercive force has a thickness t 1 , said second magnetic thin film having a higher coercive force has a thickness t 2 , and said non-magnetic thin film has a thickness t 3 , which fall in the range: 4 Å<t 2 <20 Å, 5 Å<t 1 ≦20 Å, t 1 >t 2 , and 32 Å<t 3 <50 Å, and wherein a ratio of coercive force between adjacent magnetic thin film is 1.2:l to 100:1.
Claim 8
Dependent Claim
41 words
The magnetic multilayer film of claim 5 wherein said first magnetic thin film has a squareness ratio SQ 1 of from 0.7 to 1.0, and said second magnetic thin film has a squareness ratio SQ 2 of from 0.1 to 0.8.
Claim 9
Dependent Claim
17 words
The magnetic multilayer film of claim 6 wherein SQ 2 /SQ 1 is from 0.3 to 1.0.
Claim 10
Dependent Claim
12 words
The magnetic multilayer film of claim 5 wherein t 1 <20 Å.
Claim 11
Dependent Claim
28 words
The magnetic multilayer film of claim 5 wherein 6 Å23 t 2 , t 1 ≦18 Å, t 1 ≧1.05t 2 , and 36 Å≦t 3 ≦48 Å.
Claim 12
Dependent Claim
22 words
The magnetic multilayer film of claim 5 which produces a magnetoresistive curve having a maximum hysteresis width of up to 10 Oe.
Claim 13
Dependent Claim
31 words
The magnetic multilayer film of claim 5 which produces a magnetoresistive curve having a magnetoresistant slope of at least 0.15%/Oe in the magnetic field range between -50 Oe and +50 Oe.
Claim 14
Dependent Claim
25 words
The magnetic multilayer film of claim 5 having a magnetoresistance ratio of a least 5%, said magnetoresistance ratio being defined as (maximum resistivity--minimum resistivity)/(minimum resistivity)×100%.
Claim 15
Dependent Claim
31 words
The magnetic multilayer film of claim 5 which produces a magnetoresistive curve having a magnetoresistant slope of at least 0.03%/Oe in a magnetic field with a high frequency of 1 MHz.
Claim 16
Dependent Claim
134 words
A magnetic mulitlayer film, comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first magnetic thin film having a lower coercive force has a thickness t 1 , said second magnetic thin film having a higher coercive force has a thickness t 2 , and said non-magnetic thin film has a thickness t 3 , which fall in the range: 4 Å<t 2 <20 Å, 5 Å<t 1<20 Å, t 1> t 2 , and 32 Å<t 3 <50 Å, and wherein a ratio of coercive force between adjacent magnetic thin film is 1.2:l to 100:1, and said first magnetic thin film has a composition (Ni x Fe 1-x ) y Co 1-y wherein 0.7 ≦x≦0.9 and 0.5≦y ≦1.0.
Claim 17
Dependent Claim
134 words
A magnetic mulitlayer film, comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first magnetic thin film having a lower coercive force has a thickness t 1 , said second magnetic thin film having a higher coercive force has a thickness t 2 , and said non-magnetic thin film has a thickness t 3 , which fall in the range: 4 Å<t 2 <20 Å, 5 Å<t 1<20 Å, t 1> t 2 , and 32 Å<t 3 <50 Å, and wherein a ratio of coercive force between adjacent magnetic thin film is 1.2:l to 100:1, and said first magnetic thin film has a composition (Ni x Fe 1-x ) y Co 1-y wherein 0.7 ≦x≦0.9 and 0.5≦y ≦1.0.
Claim 18
Dependent Claim
135 words
magnetic mulitlayer film comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first magnetic thin film having a lower coercive force has a thickness t 1 , said second magnetic thin film having a higher coercive force has a thickness t 2 , and said non-magnetic thin film has a thickness t 3 , which fall in the range: 4 Å<t 2 <20 Å, 5 Å<t 1 ≦20 Å, t 1> t 2 , and 32 Å<t 3 <50 Å, and wherein a ratio of coercive force between adjacent magnetic thin film is 1.2:1 to 100:1, and said second magnetic thin film has a composition (Co z Ni 1-z ) w Fe 1-w wherein 0.4 ≦z≦1.0 and 0.5 ≦w ≦1.0.
Claim 19
Dependent Claim
135 words
magnetic mulitlayer film comprising a first and a second magnetic thin film with a non-magnetic thin film between said first and second magnetic thin films, wherein said first magnetic thin film having a lower coercive force has a thickness t 1 , said second magnetic thin film having a higher coercive force has a thickness t 2 , and said non-magnetic thin film has a thickness t 3 , which fall in the range: 4 Å<t 2 <20 Å, 5 Å<t 1 ≦20 Å, t 1> t 2 , and 32 Å<t 3 <50 Å, and wherein a ratio of coercive force between adjacent magnetic thin film is 1.2:1 to 100:1, and said second magnetic thin film has a composition (Co z Ni 1-z ) w Fe 1-w wherein 0.4 ≦z≦1.0 and 0.5 ≦w ≦1.0.
Claim 20
Dependent Claim
41 words
The magnetic multilayer film of claim 5 wherein said non-magnetic thin film is formed of a member selected from the group consisting of silver, gold, copper and alloys containing at least 70% by weight of at least one of these metals.
Claim 21
Dependent Claim
52 words
A magnetic multilayer film as set forth in any one of claims 5 to 15, which is prepared by a method comprising the steps of: depositing the first and second magnetic thin films while interposing the non-magnetic thin film therebetween and effecting heat treatment at a temperature of up to 400° C.
Claim 22
Dependent Claim
23 words
The magnetic multilayer film of claim 17 wherein the deposition step is carried out under a pressure of up to 10 -8 Torr.
Claim 23
Dependent Claim
25 words
The magnetic multilayer film of claim 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, further comprising a substrate.
Claim 24
Dependent Claim
22 words
The magnetic multilayer film of claim 19, wherein said magnetic multilayer film does not have means for applying a biasing magnetic field.
References Cited (Backward Citations)
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