各向異性磁電阻、巨磁電阻測量

1、,mHelo!inlierLi_tlIeS.、hineoffoumuapenias.”,.”-ineuanayofIe_netsi.“!.meas*onlealofm,cm”,-orkftieniby,for-一”.I,!ba-ia|.power.as“partIgea”.,irmill-ntliesce”.of.-i“meomiIng.、“、y-dar-f-smpl一!”,(nma.et,”.-.-impi-,smsy,ifetepima.e.i_man_menail.itois.cail.,”Ie.enil“,maahamnious”m”.m.!ofIeguL.nbli”osareas.s

2、tbaiar,ind.：ge”.!bi.0”,.hlIeahl_b.-empl一“pa.,of35mil.kW,aninceaeof77miinkW.,IalLbiinkW,ecedings-sofmilinkWtiean.aExe_Ilebulge,aincea-of79miinkW.SeurymeauesLipanneLo.a-lNopesnalin|Lya_i.etoc-le.nomaaenta.abosaeyJerrieclisudonIlkiesepsTieimang-etsys-imp.-menIFiccsinprimitingtiepieiftieccmpaI,maingetsy

3、stBaILtieapliinaIL.pementHinifIesylopfiesamaagement.sem,improvetiesymaingetsystB,relyIe.semif-fe,ccnIollulierrig.Heiecui,rouies,fe,lupeviiinaILmangetneo.reII.，Ioie-Uisidlip.SIengIeingtielupe-iinaILmanigoetifiaIituavoainofsIeggieningtiesye-iinifoLbiLcingconIracor.CaariLouti“nga|la.umn0fsryi1speI|ns,l

4、-Ina|li1specI”-fe,prcio_uin_fe,.I.0ympc1s1aLite實(shí)驗(yàn)10.1各向異性磁電阻、巨磁電阻測量一.實(shí)驗(yàn)?zāi)康?1)初步了解磁性合金的AMR,多層膜的GMR,摻堿土金屬稀土鎰氧化物的CMR;(2)初步掌握室溫磁電阻的測量方法。二.實(shí)驗(yàn)原理一般磁電阻是指在一定磁場下材料電阻率改變的現(xiàn)象。通常將磁場引起的電阻率變化寫成Ap=p(H)-p(0),其中p(H)和p(0)分別表示在磁場H中和無磁場時(shí)的電阻率。磁電阻的大小常表示為：8芯二&xlOO%P其中p可以是p(0)或p(H)。絕大多數(shù)非磁性導(dǎo)體的MR很小，約為10-5%,磁性導(dǎo)體的MR最大為3%5%,且電阻率的變

5、化與磁場方向與導(dǎo)體中電流方向的夾角有關(guān)，即具有各向異性，稱之為各向異性磁電阻，簡記為AMR。1988年，在分子束外延制備的Fe/Cr多層膜中發(fā)現(xiàn)MR可達(dá)50%,并且在薄膜平面上磁電阻是各向同性的。人們把這稱之為巨磁電阻，簡記為GMR。1994年，人們又發(fā)現(xiàn)Fe/A2Q/Fe隧道2在4.2K的MR為30%,室溫達(dá)18%,這種大的磁電阻效應(yīng)，人們將之稱為隧道結(jié)磁電阻，簡記為TMR。20世紀(jì)90年代后期，人們?cè)趽綁A土金屬稀土鎰氧化物中發(fā)現(xiàn)MR可達(dá)103%106%,稱之為龐磁電阻，簡記為CMROI.各向異性磁電阻(AMR)一些磁性金屬和合金的AMR與技術(shù)磁化相對(duì)應(yīng)，即與從退磁狀態(tài)到趨于磁飽和過程的相應(yīng)

6、的電阻變化。外加磁場與電流方向的夾角不同，飽和磁化時(shí)的電阻率不一樣，即有各向異性。通常取外磁場方向與電流方向平行和垂直兩種情況測量AMR,即有阻=P-P(0)和叫=P-P(0)。若退磁狀態(tài)下磁疇是各向同性分布的，疇壁散射變化對(duì)磁電阻的貢獻(xiàn)較小，將之忽略，則P(0)與平均值Pav=1/3(P/+2P_l)相等。大多數(shù)材料PP(0),故區(qū)二0PtKPtK=P-P(0),Ph.offou.fape.HDUnkW,aliiceof7-mikW.，”tamikW,iigssof=mDikWth.ofmoetha,*.!.bix.e11acori、，i-1.l-,%ama，arop,fUl.lL.一.1g

7、a|la.Umi0fsryi1spciois,lo.coiiola|li1sp.cI,fe，pr一0一.，aiLI.0ympc.ba-iieuaia，ofI.curretsiloi,Us_IIDpm.itpla.bL-e,.iiceaieIIuiceptofliogelpromiIig.Le.ina、yl.fousoiimpl-eiaii,I-ae，coiliuLlyimprit.laboe,iomlri.aoiLets-IolI.ivroimetapolLioiILes,0.，frIe.iseLll.yeastomaiaisa”.togooLposLe.Llii-sfiaaiiiatorsI

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10、.，“，of一L，em01a.Caaridouti圖10.1-4些鐵磁金屬與合金薄膜的AMR曲線.實(shí)線和虛線分別表示橫向和縱向的磁電網(wǎng)I.多層膜的巨磁電阻(GMR)巨磁電阻效應(yīng)首次在Fe/Cr多層膜中發(fā)現(xiàn)，其室溫下的MR約11.3%,4.2K時(shí)約為42.7%;Co/Cu多層膜室溫MR可達(dá)60%80%,遠(yuǎn)大于AMR,故稱為巨磁電阻。這種巨磁電阻的特點(diǎn)是：(1)數(shù)值比AMR大得多。(2)基本上為各向同性。圖中高場部分的雙線分別對(duì)應(yīng)于(MR)/和(MR)1，其差值為AMR的貢獻(xiàn)。該多層膜在300K和4.2K下分別為0.35%和2.1%。約為其GMR的二十分之一。(3)多層膜磁電阻按傳統(tǒng)定義MR=P(

11、H)-P(0)/P父100%是負(fù)值，恒小于100%;常采用另一定義GMR=P(0)P(H)/P(H)父100%,用此定義數(shù)值為正，且可大于100%。(4)中子衍射直接證實(shí)，前述多層膜相鄰鐵磁層的磁化為反鐵磁排列，來源于層間的反鐵磁耦合。無外磁場時(shí)，各層Ms反平行排列，電阻最大；加外磁場后，各層Ms平行排列,電阻最小。如圖10.1-6所示。(5)多種磁性材料多層膜都有GMR,但并不是所有多層膜都有大的磁電阻，有的很小，甚至只觀察到AMR。,.Helo!.rLl_tlIeSg一、h.offou.fI!.a.Ccnfn.13UnkW,aii.eof7-mikW.，”tamikW,isof331Dik

12、Wth.ig.|l.uLm.of.I，.o|l-.Il.|li.l.clI.,一.，prui.K，.|LI.O，-.ofmoetha,*.Rel.bix.11auorilx、，i-1.l-,%rm.，I圖10.1-5為這種多層膜的磁電阻曲線。-4010.1-5Fe/Cr&層股的GMR曲線!Th加磁場無磁場加磁場圖10.多層膜中行無外磁場碳化分布與電阻變化的示意圖圖10.1-7是Si(100)/Fe(2.2nm)/Co2nm/Cu2.1nm15多層膜的磁電阻曲線。1002003002度岡loomiuoo(901圉10,1-7多后膜Si(100)/Fc2nm),Co2nm/CU2.1nmh的室溫磁

13、電陰曲戰(zhàn)1*110.l-8NA”SraMnQ,薄膜杼品的電陰率和磁電網(wǎng)隨溫度變化美系，式中MR10-1%3.摻堿土金屬稀土鎰氧化物的龐磁電阻(CMR)圖10.1-8是Ndo.7SG.3MnO3薄膜樣品的電阻率、磁電阻隨溫度變化關(guān)系。該樣品的MR106%。到目前為止，對(duì)RE4TxMnO3(RE=La,Pr,Nd,Sm；T=Ca,Sr,Ba,Pb)，在x=0.20.5范圍內(nèi)都觀測到CMR和鐵磁性。這種CMR的特點(diǎn)為:(1)數(shù)值遠(yuǎn)大于多層膜的GMR;(2)各向同性；(3)負(fù)磁電阻性，即磁場增大，電阻率降低；CMR總是出現(xiàn)在居里溫度附近(TCTJ,隨溫度升高或降低，都會(huì)很快降低;(5)目前只有少部分材

14、料的居里點(diǎn)高于室溫；(6)觀察這類材料CMR的外加磁場比較高，一般需Tesla量級(jí)。,mHelo!inlierLi_tlIeS.ahineoffoumuapenias.”,.”-ineuanayofIe_netsi.“!.meas*onlealofm,cm”,-orkftieniby,fr-一”.I,!ba-ia|.power.as“partIgea”.,irmill-ntlieif-ce|lof.i“meomiIng.、“、y-dar-f-smpl一!”,“.et,”.-.-impi-,smsy,ifetepima.e.i_man_menailcitois.cail.,”Ie.enil“,m

15、aahamnious”m.m.!ofIeguL.nbli”osareas.stbaiar,ind.：ge”.!bi.0”,.hlIeahl_b.-empl”.一mil.kW,aninceof77miinkW.,IalLbiinkW,edings-sofmilinkWtiean.aExe_Ilebulge,aincea-of79miinkW.SeurymeauesLipanneLo.a-lNopesnalin|Lya_i.etoL_le.nomaaenta.aboulinsIna-i.iatorsI.pillsofmilonYuan,beyiLtieani.abulgeof1miinYLa,b-

16、nLtieangcompan,id!m.inY-n,aiceof1-1miinYLan,*.aetatgafiu.Enegypo-esup，HaLcacompleiggkW,LiIIgnW.iegLa,poecnpIonrmilb%,LL-ssins|efrman,grraty-llcompae.tolas-r,cabingkW,sLluLiXLeII-gkW”!gkW.eienyifmoetialS*.Relabii,inexequiaeItaalaii,acoriIIJ,inceseL%foma，.ie.,uiaentIccll.ageae一%,III%re-cinoIesmepeiiLa

17、yarealerMaorlcieetsisIsioLLaLeetotieimangemet.sembbs、sIeIgIeningteLnilgicaesarC,sengIenii_eniazalsLinIila.iIinlcsaeyJerrieLinSuLIinIlkinsepsTieimangetsystBimp.-menIFicsinprimitingtiepieiftiecmpaIymannglBetsystBaILtieaplcaiinaIL.pementHinifIesylopfiesamaagement.sem,improvetiesymannglBetsystB,relzIe.s

18、emiflafe，cnIillulierrig.aele-i，rouies,lafe，iupeVsinaILmangetneo.reIi.，Ilcie-Cosolop.SIengIeingtielupe-iinaILmanigoetifiaIituavlainofsIeggieningtiesysue-iinifousoLcingLinIaLor.Ca1111g.|l.umn0fsryi1speI|ns,l|L.ih.|linspecIn,一，prcicufe，.i.0ympc-1aLite圖10.1-9是一種摻銀的La-Ca-Mn-O樣品的室溫磁電阻曲線。fl.W_fl.175-/Ea17o

19、/ang：/O.155jF(U5。,，、,1-L5-LO-0.50.00.5LOL5H(kOc)圖10.1-9種摻鍬La-Ca-Mn-O樣品的室溫磁電阻曲線三.實(shí)驗(yàn)內(nèi)容1 .實(shí)驗(yàn)儀器亥姆霍茲線圈，電磁鐵，大功率恒流電源，大功率掃描電源，精密恒流源，數(shù)字微伏表,四探針樣品夾具2 .實(shí)驗(yàn)步驟(1)將樣品垂直于磁場方向擺放；(2)打開電源，將精密恒流源調(diào)至6mA,給樣品通過恒定電流；(3)將大功率恒流電源輸出電流調(diào)至6.00A,使電磁鐵產(chǎn)生磁場；(4)逐步單向調(diào)整大功率恒流電源輸出電流至-6.00A,在此過程中注意找極值點(diǎn)，隨時(shí)調(diào)整電流變化步長，記錄調(diào)整過程中穩(wěn)定的電流值和相應(yīng)的微伏表的電壓值；(5

20、)反向調(diào)整大功率恒流電源輸出電流由-6.00A至6.00A,同上記錄數(shù)據(jù)；(6)將樣品平行于磁場方向放置，重復(fù)(3卜(5),記錄數(shù)據(jù)；(7)將所有恒流源輸出調(diào)至零，關(guān)閉電源。四.實(shí)驗(yàn)結(jié)果與分析I.數(shù)據(jù)記錄(I)當(dāng)樣品電流與外磁場相互垂直時(shí)，記錄數(shù)據(jù)如下表：輸出電流6A-6A:U/mv5.7755.7765.7775.7805.7835.7875.7915.7945.7965.797I/A65.505.154.543.582.982.542.312.061.89U/mv5.7985.8005.8035.8055.8075.8105.8155.8175.8205.826I/A1.821.701.4

21、81.351.170.940.610.520.380.13U/mv5.8305.8355.8385.8425.8435.8455.8475.8525.8575.860I/A0.03-0.15-0.22-0.32-0.34-0.38-0.4-0.49-0.55-0.60U/mv5.8635.8715.8775.8835.8725.8425.8355.8205.8145.811I/A-0.63-0.74-0.79-0.82-0.87-0.95-1.07-2.08-3.09-4.02U/mv5.8095.8085.807I/A-4.86-5.27-6.12對(duì)應(yīng)U-I曲線:,mHelo!inlierL

22、i_tlIeS.、hineoffoumuapenias.”,.”-ineuanayofIe_netsi.“!.meas*onlealofm,cm”,-orkftieniby,fr-一”.I,!ba-ia|.power.as“partIgea”.,irmill-ntlieif-ce|lof.i“meomiIng.、“、y-dar-f-smpl一!”,“.et,”.-.-impi-,smsy,ifetepima.e.i_man_menai-lNopesnalin|LyaidetoLcule.nomaaenta.aboulinsIna-i.iatorsI.pillsofmilonYuan,beynL

23、tieannuabulgeof1milinYLa,b-nLtieang.mpan,id!milinYuan,a,i.eof1-1miinYLan,*.aetatgafiu.Enegypo-esup，HaL.acompleiggkW,LiIIgnW.iegLa,poe.npIonrmi%,LL-ssins|efrmancegratyrrd.eLcompaeLtolas-r,cabingkW,sLfuLiXLeII-gkW”!gkW.，emooekiecyofmoetialS*.Relabii,inexequiaeItaaiaii,aoriIIJ,incceseL%fomayealarie.uil

24、lentIol.ageae-%,II*re-LinoIesmepeiidayarealerbaoroieetsinsioULaideetotieomangemet.sembbs、sIeIgIeningteLnolgiesarL,sengIenii_eniazalsconIoladinIinscsaeyJerrieconsuL10110knewsepsTieomangetsystBimp.-menIFoccsonpromotingtiepoeoftieccmpaI,mannglBetsystBandtieaplaionaIL.pementHonofIesylopfiesamaagement.se

25、m,improvetiesymannglBetsystB,relzIe.semoflafe,ccnIollulierriguae.,rouies,lafe,iupeVsonandmangetneo.reI|a,Ilie-Losulop.SIengIeingtielupe-ionandmanigoetofiaIituavoainofsIeggieningtiesysue-iinofousouLingconIaLor.Caarilouti1111ga|la.Umnofseury.-I|ns,11dIna|li1specI”-e,pro|iui|n_fe,“Ie0ymp-1adite5.92輸出電流

26、-6A-6AU/mv5.8095.8135.8165.8205.8255.8285.8345.8395.8445.848I/A-6-5.23-4.73-4.58-3.33-2.70-1.66-1.16-0.81-0.51U/mv5.8525.8565.8605.8655.8745.8805.8865.8935.8985.906I/A-0.43-0.23-0.050.120.330.460.550.660.720.82U/mv5.8745.8655.8535.8435.8405.8375.8355.8335.8305.829I/A0.910.951.232.042.533.043.514.045

27、.105.92U/mv5.829I/A6.10對(duì)應(yīng)U-I曲線:,mHelo!inlierLi_tlIeS.ahineoffoumuapenias.”,.”-ineuanayofIe_netsi.“!.meas*onlealofm,cm”,-orkftieniby,fr-一”.I,!ba-ia|.power.as“partIgea”.,irmill-ntlieif-ce|lof.i“meomiIng.、“、y-dar-f-smpl一!”,“.et,”.-.-impi-,smsy,ifetepima.e.i_man_menailcitois.cail.,”Ie.enil“,maahamnious”

28、m.m.!ofIeguL.nbli”osareas.stbaiar,ind.：ge”.!bi.0”,.hlIeahl_b.-empl”.一mil.kW,aninceof77miinkW.,IalLbiinkW,edings-sofmilinkWtiean.aExe_Ilebulge,aincea-of79miinkW.SeurymeauesLipanneLo.a-lNopesnalin|Lya_i.etoL_le.nomaaenta.aboulinsIna-i.iatorsI.pillsofmilonYuan,beyiLtieani.abulgeof1miinYLa,b-nLtieangcom

29、pan,id!m.inY-n,aiceof1-1miinYLan,*.aetatgafiu.Enegypo-esup，HaLcacompleiggkW,LiIIgnW.iegLa,poecnpIonrmilb%,LL-ssins|efrman,grraty-llcompae.tolas-r,cabingkW,sLluLiXLeII-gkW”!gkW.eienyifmoetialS*.Relabii,inexequiaeItaalaii,acoriIIJ,inceseL%foma，.ie.,uiaentIccll.ageae一%,III%re-cinoIesmepeiiLayarealerMao

30、rlcieetsisIsioLLaLeetotieimangemet.sembbs、sIeIgIeningteLnilgicaesarC,sengIenii_eniazalsLinIila.iIinlcsaeyJerrieLinSuLIinIlkinsepsTieimangetsystBimp.-menIFicsinprimitingtiepieiftiecmpaIymannglBetsystBaILtieaplcaiinaIL.pementHinifIesylopfiesamaagement.sem,improvetiesymannglBetsystB,relzIe.semiflafe，cn

31、Iillulierrig.aele-i，rouies,lafe，iupeVsinaILmangetneo.reIi.，Ilcie-Cosolop.SIengIeingtielupe-iinaILmanigoetifiaIituavlainofsIeggieningtiesysue-iinifousoLcingLinIaLor.Ca1111g.|l.umn0fsryi1speI|ns,l|L.ih.|linspecIn,一，prcicufe，.i.0ympc-1aLite將兩圖合并到同一圖中有:(2)當(dāng)樣品電流與外磁場相互平行時(shí)，記錄數(shù)據(jù)如下表:輸出電流6A-6A:U/mv6.1216.1166

32、.1116.1036.0896.0706.0576.0346.0216.004I/A6.044.743.873.001.891.000.580.07-0.14-0.34U/mv5.9995.9935.9855.9775.9725.9665.9605.9565.9505.961I/A-0.40-0.46-0.53-0.59-0.62-0.68-0.72-0.74-0.79-0.82U/mv6.0146.0356.0486.0736.0866.0966.1176.1276.1326.134I/A-0.89-0.96-1.06-1.46-1.82-2.21-3.65-4.79-5.75-6.16對(duì)應(yīng)

33、U-I曲線:輸出電流-6A-6AU/mv6.1366.1356.1296.1206.1086.0896.0586.0456.0406.030I/A-6.06-5.63-4.50-3.33-2.21-1.14-0.27-0.040.040.19U/mv6.0266.0186.0065.9965.9865.9775.9725.9665.9605.967I/A0.250.360.470.560.630.690.730.760.800.84U/mv6.0286.0486.0856.1106.1166.1266.1306.1346.1386.138I/A0.911.001.592.573.013.904

34、.605.185.936.01對(duì)應(yīng)U-I曲線:合并到同一圖中有:I2.數(shù)據(jù)分析,.Heio!.rLl_tlIeSg一、h.offou.fape.HDUnkW,aliiceof7-mikW.，”tamikW,iigssof=mDikWth.ofmoetha,*.!.bix.e11acori、，i-1.l-,%ama，arop,fUl.lL.一.1ga|la.Umi0fsryi1spciois,lo.coiiola|li1sp.cI,fe，pr一0一.，aiLI.?！币?ba-iieuaia，ofI.curretsiloi,Us_IIDpm.itpla.bL-e,.iiceaieIIuicepto

35、fliogelpromiIig.Le.ina、yl.fousoiimpl-eiaii,I-ae，coiliuLlyimprit.laboe,iomlri.aoiLets-IolI.ivroimetapolLioiILes,0.，frIe.iseLll.yeastomaiaisa”.togooLposLe.Llii-sfiaaiiiatorsIIIp.ltsofmiloi、-i,b.yiLth.aiil.b.-eof,-miiiYLa,beyiLth.aigcompaiyi.!m.iiY一met.sembbs、si.Igl.iigteiolgiaesar,seigl.ihiid.ihazarsc

36、oilolaLilissa-JerrieloiisuL10110kiesepsTh.oa,oetsysfrimp.-m.ilFosoipromotig，.po.ofth.mpaIymai-lmetsystBaiLth.apIaioiaILimpem.italoiofI.og/kW,Lo11gikW.ie.La，po.ismpioiriI、dUat-ssois|efrmaigrrat，uLcompaeLtolasr,caboiIHgikW,suluLiXL.II-gikW“IIDgikW.s，lopfiesamaagem.it.sem,improv.th.s，maiigoetsyso,relzI

37、.semoflafe，iiolFUrh.rr.u.e.，roui.s,lafe，iupeVsoiaiLmaigetieo.reII.，Ilheosldlop.，I.igieig，.lupe-ioiaiLmaiigoetofhaIitu.vo.ioiofsieggh.iiigth.s，sue-iIiofousouiigcoiiaCor.，“，ofsfemo1.Caaridouti計(jì)算：當(dāng)掃描電源電流按照6A-6A-6A變化，不論電流方向與磁場方向垂直還是平行，圖像都會(huì)出現(xiàn)雙峰，且峰值沒有與零點(diǎn)重合，這是由于材料的磁滯現(xiàn)象引起的。由于電流I保持不變，為6mA,電壓V的變化亦為電阻R的變化。對(duì)于給定

38、的合金材料，在測量中，忽略溫度導(dǎo)致的線度改變，可以認(rèn)為電阻率變化的比值與電阻變化的比值相等同。因此R-H曲線亦可用U-I曲線表示。電流與磁場垂直時(shí)，峰值為樣品完全退磁時(shí)的電阻，即R),對(duì)應(yīng)Uo；電阻隨磁場變化趨于的穩(wěn)定值為樣品的垂直磁電阻，即R1,對(duì)應(yīng)Uo對(duì)兩個(gè)峰值和四個(gè)穩(wěn)定值分別求平均，可得:5.8835.906Uo二2=5.8945mV,U,=5.7755.8075.8095.829=505mVP-P.AMR=；。R/_R_U/-Ui.U/-U_&一一U0一(Uh7Uhj72U0100%6.132-5.805(5.9556.132)/2100%=5.41%電流與磁場平行時(shí)，谷值為樣品完全退

39、磁時(shí)的電阻，即R0,對(duì)應(yīng)U0;電阻隨磁場變化趨于的飽和值為樣品的平行磁電阻，即R,對(duì)應(yīng)U。對(duì)兩個(gè)谷值和四個(gè)飽和值分別求平均，可得:5.9505.960U0/二-26.1216.1346.1366.138=5.955mV,U=6.132mV分析:(1)由以上數(shù)據(jù)，易得-U/2U-U0U。PavRRavHUav1=5.194mV,P0KR0oCU0=0/u=5.2975mV32可見，耳和P0并不相等，這說明樣品在退磁狀態(tài)下有磁疇織構(gòu)，即磁疇分布并非完全各向同性。(2)由圖，顯然隨著測量時(shí)間的推移，測得的磁電阻曲線有明顯向高電阻方向移動(dòng)的趨勢。這是由于樣品通電后會(huì)產(chǎn)生焦耳熱，隨著時(shí)間的推移，樣品溫度

40、逐漸升高，電阻率變大,熱效應(yīng)不再可以忽略，以至當(dāng)一個(gè)測量周期完成時(shí)，電阻率增幅可高達(dá)到1%左右，而實(shí)驗(yàn)最終的AMR也不過才3.3%,可見測量時(shí)間越長，由熱效應(yīng)引起的誤差越大越不可忽略。(3)試驗(yàn)并沒有直接測量沒有外磁場時(shí)樣品的電阻，這是由于樣品此前已經(jīng)過多次實(shí)驗(yàn)，有一定的不確定剩磁，因而實(shí)驗(yàn)采用測量曲線中的峰值或谷值作為樣品完全退磁時(shí)的電阻。但在實(shí)驗(yàn)中，峰值或谷值附近電阻變化極大，測量選擇的步長并不能保證實(shí)驗(yàn)恰好記錄到真正的峰值或谷值，從而給實(shí)驗(yàn)帶來誤差。(4)樣品的剩磁會(huì)使外磁場為零時(shí)的磁電阻并不對(duì)應(yīng)于樣品完全退磁時(shí)的電阻，因而磁電阻曲線會(huì)出現(xiàn)雙峰或雙谷。在理想情況下，雙峰或雙谷應(yīng)關(guān)于原點(diǎn)對(duì)

41、稱，但在該實(shí)驗(yàn)中，,mHelo!inlierLi_tlIeS.、hineoffoumuapenias.”,.”-ineuanayofIe_netsi.“!.meas*onlealofm,cm”,-orkftieniby,fr-一”.I,!ba-ia|.power.as“partIgea”.,irmill-ntlieif-ce|lof.i“meomiIng.、“、y-dar-f-smpl一!”,“.et,”.-.-impi-,smsy,ifetepima.e.i_man_menai-lNopesnalin|LyaidetoLcule.nomaaenta.aboulinsIna-i.iatorsI

42、.pillsofmilonYuan,beynLtieannuabulgeof1milinYLa,b-nLtieang.mpan,id!milinYuan,a,i.eof1-1miinYLan,*.aetatgafiu.Enegypo-esup，HaL.acompleiggkW,LiIIgnW.iegLa,poe.npIonrmi%,LL-ssins|efrmancegratyrrd.eLcompaeLtolas-r,cabingkW,sLfuLiXLeII-gkW”!gkW.，emooekiecyofmoetialS*.Relabii,inexequiaeItaaiaii,aoriIIJ,incceseL%fomayealarie.uillentIol.ageae-%,II*re-LinoIesmepeiidayarealerbaoroieetsinsioULaideetotieomangemet.sembbs、sIeIgIeningteLnolgiesarL,sengIenii_eniazalsconIoladinIinscsaeyJerrieconsuL10110knewsepsTieomangetsystBimp.-menIFoccsonpromotingtiepoeoftieccmpaI,mannglBetsystB