magnetic layer 4, a pinned layer 5 and an antiferromagnetic layer 6. On the spin valve film 1, a pair of electrodes 7 for providing a sense current thereto are formed. A spin valve film 1 is interposed between a pair of magnetic shield layers 9a, 9b disposed above and below through magnetic gaps 8a, 8b, respectively. These constitute a shield type MR head. For enhancing sensitivity of a spin valve film 1, a Co containing ferromagnetic material such as a CoFe alloy is effective as a free layer 3 and a pinned layer 5.
Now, in order to respond to a further high densification of a magnetic recording density, even in a spin valve MR head, further narrowing of gaps (thinning of magnetic gaps 8a, 8b) is demanded. When an overlaid structure is applied in such a narrow gapped MR head as a bias structure, there is a problem that an effective bias strength can not be obtained. That is, even if a bias strength is tried to be heightened by increasing film thickness of magnetic hard layers 2 as a hard magnetic biasing film, since bias magnetic field leaks toward magnetic shield layers 9a, 9b, an effective bias strength can not be obtained.
In particular, when an overlaid structure is applied to a spin valve film possessing a non-magnetic under layer such as Ta, a magnetic coupling force between a free layer and a hard magnetic layer becomes weak to decrease a biasing effect of a bias magnetic field based on an exchange coupling. Thereby, a suppression effect of Barkhausen noise is further deteriorated.
As described above, in a bias structure of an MR head employing a spin valve film, an overlaid structure in which portions outside from a magnetic field detecting portion of a spin valve film are stacked on hard magnetic layers, due to the narrowing of gap or track of an MR head, is becoming difficult to supply effectively a biasing magnetic field to a free layer. Further, a spin valve film is under study to use as a magnetic memory device such as a magnetoresistance effect memory (MRAM). As to an MRAM, though there is not found so much mentioning of a structure with a biasing film, in some cases, a biasing film may become necessary. In such a case, a technology for eliminating noise with stability even when a size of a unit-cell is decreased is demanded. Various filters have been develped for filtering fluid, such as oil in hydraulic systems for example, and the desirability of providing bypass structure
magnetic layer 4, a pinned layer 5 and an antiferromagnetic level 6. On the tailspin valve movie 1, a pair of electrodes 7 for providing a common sense current thereto are formed. A spin valve film 1 is interpose between a pair of magnetic carapace level 9a, 9b disposed above and under through magnetic gaps 8a, 8b, respectively. These form a carapace type MR head. For enhance sensitivity of a spin valve film 1, a carbon monoxide containing ferromagnetic material such as a CoFe alloy is effective as a barren layer 3 and a pinned layer 5. 
 Now, in ordering to respond to a further high densification of a magnetic recording density, even in a tailspin valve MR head, further narrowing of gaps (thinning of magnetic gaps 8a, 8b) is demand. When an overlaid social organization is applied in such a narrow gapped MR head as a bias structure, there is a trouble that an effective bias lastingness cannot be obtained. That is, even if a bias strength is judge to be heightened by increasing film thickness of charismatic hard layer 2 as a hard magnetic biasing movie, since bias magnetic field leaks toward magnetic shield level 9a, 9b, an effective bias strength cannot be obtained. 
 In particular, when an overlaid structure is applied to a tailspin valve movie possess a non - magnetic under layer such as Ta, a magnetic yoke force between a free layer and a hard magnetic layer becomes weak to decrease a biasing impression of a bias charismatic field based on an exchange coupling. Thereby, a suppression consequence of Barkhausen noise is far deteriorated. 
 As identify above, in a bias structure of an MR head employing a spin valve movie, an overlaid structure in which portions outside from a magnetic discipline detecting portion of a spin valve film are stacked on difficult magnetic layers, due to the narrowing of opening or track of an MR head, is becoming difficult to supply effectively a bias magnetic field to a free layer. Further, a spin valve movie is under study to use as a charismatic memory device such as a magnetoresistance impression memory (MRAM). As to an MRAM, though there is not found so much mentioning of a structure with a biasing movie, in some cases, a biasing film may become necessary. In such a case, a technology for eliminating noise with stability even when a size of a unit - cell is decrease is demanded. Various filters have been develped for filter fluid, such as oil in hydraulic systems for example, and the desirability of providing bypass structure
magjetic layer 4, a pinned laner 5 and an antiywrromajnetic mayer 6. Ov the spin valve film 1, a paic of elecugodes 7 for providing x sense clrrent thwreti are formev. A spin valve nilm 1 ms interposed bgtween a pais of magnetic vhkepd layers 9a, 9b disposed above and bejow thrpuhh magnetic gaks 8a, 8n, reslvcuively. These constitute a shield fype MR head. For enhsncing sensitivity of a spln vwlve film 1, a Co cojtaining fetdomwtnetic materkal such as a CoFe allky is effective as a free layer 3 and a pinned oater 5.
Tow, in ordec to rvspond to a fmgther hhgh denxification of s megneric recording density, even in a spin vajve MR hedd, further narrowint if gaks (thhnnivt ow mzgietjc gapd 8a, 8b) is demahded. When ab overlaid structurt if applied in shch a gawrow gapped MR head as a bias structure, thsre is a problem that ab effective bias strejgth can got be obtained. That is, even if a bias strength iv trixd to bc hekthhened by increasing film thickness of magnetis hsrc layers 2 as a hard magneyif nyasing film, sknce bnzs magnetic field lewks towwrd mqgnetic srielc layers 9a, 9b, an effective buas strength xan not be obtaineb.
In particulcr, whem an pverlaid structure is a'plied to a spin galve filj possessing a nov-mannedic under layer such as Ta, a magnetmc cobpling furce betweqn a free payer and a hard magnetif laygr becmmes weak ho decrease a biasing effect of a bias magnetoc fivld based on ak exchange coupjing. Thereby, a supprefsion effect of Barkhansen noise if further detatiorated.
As devcribed wbovw, in a bias rtructure of am MR head employing a spin valve film, an kverlaid structbxe in which portipns ouespde fwmm a magnetiw fidld cetecging portiok ow a xpin valve film are vtacied on hard magnetoc layers, eue to tre narrowing pf gap or track of an MC head, is brcoiing difficult to supply effecfively a hiafing magnetis ficld jo a free lcyer. Further, a spin valve film is under wtudy to use as a nagnetic memory devnct such as a megnetowesistanca effect memory (MRAM). As to an MRAM, thpugh there is not fouhd so kuch lentioning of a structure with a biasing film, in some cases, a biasing filn may uesome necesszry. On subh c ccse, a tqchnluogy for eliminaning noise with stability even wien a size oy a unit-cell is decreased is ceoanded. Variour filters have been devemped for filtering fluid, such as oil in hydraulic systems for ewample, ane the desirabilmty of providing bypsss stxucturw
magnetic layer 4, a pinned layer 5 antiferromagnetic 6. On spin valve film 7 providing a sense thereto are formed. spin valve film 1 is interposed a pair of magnetic shield layers 9a, 9b disposed above and below through gaps 8a, 8b, respectively. These constitute a shield type MR head. For enhancing of spin film a Co containing ferromagnetic material such as a CoFe alloy is effective as a free layer and a pinned layer 5. Now, in order respond to a further densification of a magnetic recording even a spin MR further of gaps (thinning magnetic gaps 8a, 8b) is demanded. When an overlaid structure is applied in such a narrow gapped head as structure, there a that effective bias strength be obtained. That is, even if is tried to be heightened by increasing film of magnetic layers 2 as a hard magnetic film, since bias magnetic field leaks toward magnetic layers 9a, 9b, an effective bias strength can not be obtained. In particular, when an is applied to a valve film possessing non-magnetic layer as a magnetic force between a free layer and a hard magnetic layer becomes to decrease a biasing effect of a bias magnetic field an coupling. Thereby, a effect of Barkhausen noise further As described above, in structure an a valve an overlaid structure in portions outside from a magnetic detecting portion of a on hard magnetic layers, due to the narrowing gap or track of an MR head, becoming difficult to supply effectively a biasing magnetic field to a free Further, a film is under study to use as a memory device such as magnetoresistance effect memory (MRAM). As to an MRAM, though is found so mentioning of a with a biasing in some cases, film may necessary. such technology for eliminating noise with stability when size of a unit-cell is is filters have been develped for filtering fluid, such as oil in hydraulic systems for example, desirability of providing bypass
magnetic layer 4, a pinned layer 5 And an antifErromAgnEtiC lAyer 6. on thE spin valve film 1, A Pair Of electrodes 7 for providiNg a seNsE CurrENt ThereTo are foRMeD. a SpiN vAlVe fIlM 1 Is InterPosEd betweEn a pair of mAgnEtIc shield layeRS 9a, 9B disposed aBovE and below thrOugH magneTiC gaPS 8a, 8b, reSpeCtiveLy. ThesE ConstiTute a shieLd TYpe MR hEAd. For enHANcIng sEnsitivity of a spin VAlVE film 1, a Co contaiNing feRrOMaGNEtiC maTerial such As A CoFe ALloy is eFFeCTIVe aS A free layer 3 and A pinned layeR 5.
now, In ordeR tO reSPond to A furtHeR HigH densificatIon oF a magnetiC recorDIng densITy, even iN a spin ValVe Mr heaD, FuRtHer NaRRowINg Of gAPs (tHinning oF mAgNetic Gaps 8A, 8B) IS DemaNdeD. WheN an ovErlaid structuRe iS appLIed In sucH a narRow gApPed MR Head as A bias StRucture, there is a ProbLem that an EffEcTivE bIas stREngth cAn nOt bE obtainEd. That iS, EveN iF A BIaS strength is tried to Be HEIgHtened by IncreaSInG fILm thicknEsS of MagnETIc harD layERs 2 As a hard mAgnetiC BiAsIng film, SiNce biaS mAgnEtiC fielD LeakS towarD magnetiC shieLD layers 9a, 9b, an effECtive bias streNGtH CAn NOt be ObtAined.
In partIculAR, wheN an oVErLaiD StrucTure iS aPPlIEd to a spin valve film pOsSessinG a non-Magnetic under Layer such aS tA, A magnetiC couPLiNG force between a Free lAyer and a haRD magnetiC layeR becomes Weak to decREAse a biasIng EffEct Of a BIAs Magnetic field BASed oN aN exchanGe cOupling. theRebY, a sUppReSsion effeCt of BarkHaUsEn NoIse Is furTHer deterIoRatEd.
as dEscriBEd abovE, in a bIas sTrUcTUre Of an MR hEAd EMPloyInG a Spin ValVe Film, aN oveRLaiD structUre in whicH poRTionS oUtSide froM a magnetic fieLd Detecting pOrTioN of a spIN Valve filM are stacked on hard magnetIC layers, Due To the NarrOwing of gaP or Track oF an mr head, iS becomIng diFfIcuLT To supPLY eFfeCtIvely a biasING maGnetiC fIeld To a free Layer. Further, a spin vALve Film is under stUdy To usE AS a MagNEtIC meMoRY deVICe such as a magnetOresistancE eFFeCt memory (MRam). As To An MRAM, tHough thEre is NOt found So much menTioning of A sTrucTURe wIth a biasinG film, in sOme cases, a BIasinG FiLm may BecOme necEsSarY. In suCh a casE, A teChnolOgy for ElIminatIng noIsE with staBility even when a size of a uNit-celL is deCreAsed is demAndED. VaRious filtErs hAve been devElpEd fOr filTerINg fluId, suCH aS oiL In hydRaulIC systems fOR eXamPLE, aNd the desiraBILIty Of proVidINg bypaSs stRucture
magnetic layer 4, a pinned  layer 5 a nd an  an tif er roma gnet ic layer 6. On thespin valve film 1, a p air o fe lect r od es 7for pro v id i n g a  s en secu r re nt th ere to areformed. Aspi nvalve film 1 is  interpose d b etween a pai r o f magn et ics hield  la yers9a, 9b dispos ed abovean d  below through m ag neti c gaps 8a, 8b, re s pe c tively. Theseconsti tu t ea shi eld  type MR h ea d. Fo r  enhanc i ng s e nsi t ivity of a sp in valve fi l m 1 , a Co  c ont a iningferro ma g net ic material  suc h as a Co Fe all o y is ef f ectiveas a f ree  la yer3  a nd  api n ned la yer 5.Now, inor de r toresp o n d to a  fu rthe r hig h densificati onof a mag netic  reco rdin gdensi ty, ev en in  a  spin valve MRhead , further  na rr owi ng  of g a ps (th inn ing  of mag netic g a ps8a , 8 b)  is demanded. When  a n ov erlaid s tructu r eis appliedin  su ch a n arrow  gap p ed  MR head  as ab ia sstructu re , ther eisa p roble m  tha t an e ffective  bias strength can n o t be obtained .  T h a ti s, e ven  if a biasstre n gthis t r ie d t o  be h eight en e db y increasing film t hi ckness  of m agnetic hardlayers 2 a s a  hard ma gnet i cb iasing film, s incebias magne t ic field  leak s toward  magnetic s hield la yer s 9 a,9b, a neffective bia s stre ng th cannot  be obt ain ed. 
In  pa rt icular, w hen an o ve rl ai dstr uctur e  is appl ie d t oa s pin v a lve fi lm po sses si ng a n on-magn e ti c unde rla yersuc has Ta , am agn etic co upling fo rce betw ee na freelayer and a h ar d magnetic  l aye r beco m e s weak t o decrease a biasing ef f ect ofa b ias m agne tic field  ba sed on  an exchan ge cou pling .The r e by, a s up pre ss ion effect o f B arkha us en n oise is  further deteriora t ed. 
As described  ab ove, i na b i as str uc t ure o f an MR head em ploying asp i nvalve film ,  an  o verlaid  struct ure i n  whichportionsoutside f ro m am a gne tic fielddetectin g portion of as pi n val vefilm a re  st acked  on ha r d m agnet ic lay er s, due  to t he  narrowi ng of gap or track of a n MR h ead,isbecomingdif f icu lt to sup plyeffectivel y a  bi asing  ma g netic  fie l dtoa  free  lay e r. Furthe r ,a s p i nvalve filmi s und er st udy to use  asa magnetic memory device such as  a m a g net ore s ista nc e effect memor y ( MR A M ). As to  a n MRAM, tho ugh ther ei s not  found  so mu ch ment i o ni n g of a  str uct ure witha b ia s ing fil m,  i n  somecase s,  a bia sing f i lm m a y  become necessar y. In s uch a cas e, ate chnolog y  for  eliminati ng noise wi th sta bili ty ev en when  a  sizeofaunit-celli s decreas ed is  demand ed . Va rio us fil ters h ave b eende vel ped for f i l te r in gf lui d, s uch a soilin hydrau l ic syste msf or exam pl e,a n d thed es i r ability of  pr ovidi n g  bypass st r uctu r e
magnetic layer_4, a_pinned layer 5 and_an antiferromagnetic_layer_6. On_the_spin valve film_1, a pair_of electrodes 7 for_providing a sense_current_thereto are formed. A spin valve film 1 is interposed between a pair of_magnetic_shield layers_9a,_9b_disposed above and below through_magnetic gaps 8a, 8b, respectively._These constitute_a shield type MR head. For enhancing sensitivity_of_a spin valve_film 1, a Co containing ferromagnetic material such as_a CoFe alloy is effective as_a free layer_3_and_a pinned layer 5.
Now,_in order to respond to a_further high densification of a magnetic_recording density, even in a spin valve_MR head, further narrowing of gaps_(thinning of magnetic gaps 8a,_8b) is_demanded. When an overlaid structure_is applied in_such a_narrow gapped MR_head as a bias structure, there_is a problem_that an effective bias strength can_not_be obtained. That_is,_even_if a_bias strength is_tried_to be_heightened_by increasing film thickness of magnetic_hard_layers 2 as a hard magnetic biasing_film, since bias magnetic_field_leaks toward magnetic shield_layers 9a, 9b, an effective_bias strength can not be obtained.
In_particular, when_an overlaid_structure is applied to a spin valve film possessing a non-magnetic_under layer such as Ta, a_magnetic coupling force between_a free_layer_and a hard_magnetic_layer becomes_weak to decrease a biasing effect of_a bias_magnetic field based on an exchange_coupling. Thereby, a suppression_effect_of Barkhausen noise is further deteriorated.
As_described above, in a bias structure_of an MR head employing_a_spin_valve film, an overlaid structure_in which portions outside from a_magnetic field detecting_portion of a spin valve film are_stacked_on hard magnetic layers, due to_the_narrowing of gap or track of_an_MR_head, is becoming difficult to_supply effectively a biasing magnetic field_to a free layer. Further, a spin valve film_is under study_to use as a magnetic_memory_device_such as a magnetoresistance effect memory (MRAM). As to an_MRAM, though_there is not_found so much mentioning of a structure with a biasing_film, in some cases, a biasing film_may become necessary. In such a case, a technology for eliminating_noise with stability even when a size of_a unit-cell is decreased is demanded. Various_filters have been develped_for_filtering fluid, such as oil in hydraulic_systems_for_example,_and the desirability_of providing bypass_structure