^ ^ H ^ I H ^ H ^ II ^ II ^ H ^ H ^ ^ ^ ^ ^ H ^ ^ ^ ^ HI I ^ European Patent Office � Office europeen des brevets EP 0 777 214 A3

EUROPEAN PATENT APPLICATION

(88) Date of publication A3: (51) |nt CI * G1 1 B 5/39, G1 1 B 5/012 11.11.1998 Bulletin 1998/46

(43) Date of publication A2: 04.06.1997 Bulletin 1997/23

(21) Application number: 96308390.2

(22) Date of filing: 20.11.1996

(84) Designated Contracting States: (72) Inventor: Mallary, Michael L. DE FR GB IT NL Berlin, Massachusetts 01503 (US)

(30) Priority: 30.11.1995 US 565032 (74) Representative: Goodman, Christopher Eric Potter Clarkson, (71) Applicant: QUANTUM CORPORATION Park View House, Milpitas California 95035 (US) 58 The Ropewalk Nottingham NG1 5DD(GB)

(54) Longitudinally biased magnetoresistive sensor having a concave shaped active region to reduce Barkhausen noise by achieving a substantially single magnetic domain state

(57) A magnetoresistive ("MR") sensor (100) con- the off-track boundary. In a preferred embodiment, a structed with a concave shaped edge (102) in order to substantially constant effective longitudinal bias field provide an effective longitudinal bias field in the center may be obtained throughout the active MR element if of the active MR element sufficient to obviate multi-do- the stripe height increases as an exponential function of main states and concomitant Barkhausen noise. Utiliz- the square of the off -track distance. The principles of the ing the concave shape proposed herein, the "stripe present invention are likewise applicable to use in spin height" of the element is at a minimum (SHMIN) in the valve ("SV") and other giant magnetoresistive ("GMR") center of the active region (ARL) and increases toward sensors.

Printed by Jouve, 75001 PARIS (FR) EP 0 777 214 A3

Patent Number European EUROPEAN SEARCH REPORT Application Office EP 96 30 8390

DOCUMENTS CONSIDERED TO BE RELEVANT Category Citation of document with indication, where appropriate, Relevant CLASSIFICATION OF THE of relevant passages to claim APPLICATION (lnt.CI.6) PATENT ABSTRACTS OF JAPAN 1,10,11,1 G11B5/39 vol. 095, no. 007, 31 August 1995 20,21,30 G11B5/012 & JP 07 110921 A (CITIZEN WATCH CO LTD), 25 April 1995 * abstract *

GB 2 134 307 A (MAGNETIC PERIPHERALS INC.) I, 5,10, 8 August 1984 II, 15, 20,21, 25,30 * page 2, line 43 - line 127; figure 1A * PATENT ABSTRACTS OF JAPAN 1,10,11, vol. 012, no. 406 (P-777), 27 October 1988 20,21,30 & JP 63 142511 A (FUJITSU LTD), 14 June 1988 * abstract *

EP 0 585 008 A (SEAGATE TECHNOLOGY 1,11,21 INTERNATIONAL) 2 March 1994 * column 7, line 11 - line 42 * TECHNICAL FIELDS SEARCHED (lnt.CI.6) GB 2 272 561 A (ROCKY MOUNTAIN MAGNETICS 1,11,21 G11B INC) 18 May 1994 * page 13, line 11 - page 14, line 25; figures 10,11 *

EP 0 675 371 A (YAMAHA CORPORATION) 31,40 4 October 1995 * page 8, line 32 - line 45 *

The present search report has been drawn up for all claims Place ol search Dale of completion of the search Examiner BERLIN 14 September 1998 Gerard, E CATEGORY OF CITED DOCUMENTS T : theory or principle underlying the invention E : earlier patent document, bul published on, or X : particularly relevant if taken alone after the filing date Y : particularly relevant if combined with another D : document cited in the application document of the same category L ; document cited for other reasons A : technological background O : non-written disclosure & : member of the same patent family, corresponding P : intermediate document document

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