Magnetic sensor, production process of the magnetic sensor and magnetic array suitable for the production process

• US 7,598,835 B2
• Filed: 05/10/2005
• Issued: 10/06/2009
• Est. Priority Date: 10/23/2002
• Status: Expired due to Fees

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Wakui, Yukio, Oohashi, Toshiyuki
• Primary Examiner(s): Enad; Elvin G
• Assistant Examiner(s): Rojas; Bernard
• Application Number:
  US11/125,100
• Publication Number:
  US 20050212632A1
• Time in Patent Office: 1,610 Days
• Field of Search: 335/215, 335/306, 324/252, 324/260, 360317-322
• US Class Current: 335/215
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: H01F 10/324 Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
• CPC Class Codes: H01F 10/3295 Spin-exchange coupled multilayers wherein the magnetic pinned or free layers are laminated without anti-parallel coupling within the pinned and free layers
• CPC Class Codes: H01F 13/00 Apparatus or processes for magnetising or demagnetising devices for holding workpieces using magnetic or electric force acting directly on the workpieces B23Q3/15 ; for degaussing ships B63G9/06; for clocks or watches G04D9/00; recording or erasing of information on magnetic record carriers G11B5/00 ; demagnetising arrangements for colour television H04N9/29
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49034 Treating to affect magnetic properties

Abstract

The present invention aims to provide a magnetic sensor provided with a magnetoresistive effect element capable of stably maintaining a direction of magnetization in a magnetic domain of a free layer.

The magnetic sensor includes a magnetoresistive effect element provided with narrow zonal portions 11a . . . 11a including a pinned layer and a free layer. Disposed below both ends of the free layer are bias magnet films 11b . . . 11b composed of a permanent magnet that applies to the free layer a bias magnetic field in a predetermined direction and an initializing coil 31 that is disposed in the vicinity of the free layer and applies to the free layer a magnetic field having the direction same as that of the bias magnetic field by being energized under a predetermined condition. Further, magnetizing the bias magnet films and fixing the direction of magnetization of the pinned layer are performed by a magnetic field formed by a magnet array configured such that plural permanent magnets are arranged on a lattice point of a tetragonal lattice and a polarity of a magnet pole of each permanent magnet is different from a polarity of the other adjacent magnet pole spaced by the shortest route.

Claims

1. A magnetic sensor comprising:

a plurality of full-bridge-connected giant magnetoresistive effect elements, each giant magnetoresistive effect element having a spin valve film including a pinned layer, a conductive spacer layer, and a free layer,

wherein the spin valve films have narrow zonal portions each of which extends in the longitudinal direction comprising;

bias magnet films provided at both ends of the free layer in the longitudinal direction for producing in the free layer a bias magnetic field in the longitudinal direction of the free layer, whereby the direction of magnetization in each magnet domain in the free layer can stably be maintained in the predetermined direction when an external magnetic field is not present, and

initializing coils being energized under a predetermined condition to thereby generate an initializing magnetic field for returning the direction of magnetization in each magnetic domain in the free layer to the longitudinal direction of the free layer, whereby the direction of magnetization in each magnetic domain in the free layer can assuredly be returned to the initial state even if the direction of magnetization is disturbed by applying a strong magnetic field to the free layer.

2. A magnetic sensor comprising:

a plurality of full-bridge-connected giant magnetoresistive effect elements, each giant magnetoresistive effect element having a spin valve film including a pinned layer, a conductive spacer layer, and a free layer,

wherein free layer comprises;

a bias magnet film composed of a permanent magnet for producing a bias magnetic field in the free layer in a predetermined direction so that the direction of magnetization in each magnetic domain in the free layer can be maintained in the predetermined initial state direction; and

an initializing coil that is provided in the vicinity of the free layer and applies to the free layer an initializing magnetic field in the direction same as the direction of the bias magnetic field by being energized under a predetermined condition so that the direction of magnetization in each magnetic domain in the free layer can assuredly be returned to initial state direction even if the direction of magnetization is disturbed by applying a strong magnetic field to the free layer.