Tieu ban Khoa hgc vdt lieu ISBN: 978-604-913-C ' 1-3<br />
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<br />
HIEU iTNG TlT DIEN TRO KHONG LO CUA DA LOP Ni-Co-Cu KET<br />
TUA B A N G D I E N H O A<br />
<br />
Pham Trung San, Truong Anh Khoa, Ngo Qu6c Quyen<br />
Vien Nghien cuu va Ung dung Cdng nghe Nha Trang<br />
02 - Himg Vuong - Nha Trang<br />
Email: phamtrungsan@gmail.com<br />
<br />
Tom tat<br />
Kit tua diin hda md ra khd ndng cho viic chi tao hi mdng da lap tir diin trd<br />
khdng Id GMR) cdu triic nanomet rdt hiiu qud vdi gid thdnh re. Trong nghiin ciru<br />
ndy chiing tdi gidi thiiu vi hiiu itng lit diin trd khdng Id a mdng da lap Ni-Co-<br />
Cu/Cu kit lua trin di n-Si tit mdt dung dich diin phdn chita cdc cation Cu2*, Ni2^<br />
vd Cof bdng phuang phdp mg xung ddng nhu mdt hdm sd cua biin do xung kit<br />
tua lap tit tinh (Ni-Co-Cu) vd lap khdng tir linh (Cu). Kit qud cho thdy thdnh<br />
phdn lcrp lit linh vd hiiu itng GMR cita da lap phu thude lan vdo biin do xung khi<br />
diin lugng khdng thay ddi. Hiiu itng tit diin Ird khdng Id tgi nhiit do phdng Ihu<br />
dugc a Idt ca cdc mdu vd dgt gid tri egg nhdt tdi 7%> trong viing lir trirdng 3kOe<br />
khi biin do xung kit tua lap tit tinh vd khdng lir linh Id 480mA/cm vd 2mA/cm .<br />
Viic khdo sdt cdc ddc tinh cdu trite ciia hi mdng bdng XRD, EDX, SEM vd AFM<br />
cho thdy cd mdi quan hi tuang quan giua thdnh phdn, hinh ihdi ciia da lcrp vd<br />
hiiu itng MR thu dugc.<br />
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Abstract<br />
ElectrodeposUion opens the possibility of efficient and inexpensive fabricadon<br />
of magneto-resistive (GMR) nanostructured multUayer. In this paper, we report<br />
GMR in Ni-Co-Cu- Cu mullUayers deposited gn n-Si from a single electrolyte<br />
containing Cu2^, Ni2^ and Co2^ by a galvanostalic hvo-pulse plating method as a<br />
function of the current amplitude for deposition magnetic (Ni-Co-Cu) and non-<br />
magnetic (Cu) layers. Result showed that the composition of magnetic layer and<br />
GMR effect of multilayer was highly influenced by applied current amplitude<br />
when passing electric charges were fixed constantly. A giant magnetoresistance<br />
(GMR) effect at room temperature was observed in all samples and a maximum<br />
GMR of 7% measured at 3 kOe could be achieved with current amplitude for<br />
deposition magnetic and non-magnetic layers at 480mA/cm^ and 2mA/cm^.<br />
Structural characterization by XRD, EDX, SEM and AFM has also revealed a<br />
correlation between Ihe composition and morphological nanostructure of the<br />
multUayer and the observed MR effect.<br />
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<br />
I. Mo dau<br />
Vat lieu mang mdng tir tinh (cung va mim) ngay cang dugc sir dung rdng rai trong nhilu<br />
ITnh virc nhu tir dien tir (trong cdng nghe IC) va tir dien ca (cbl tao cac vi linh kien MEMS)<br />
ciing nhu trong mdi trudng luu trir sd lieu (che tao cac diu ghi va dpc thdng tin).<br />
Tuy theo ddi tugng sir dung, vat lieu mang mdng dugc cbl tao bing cdng nghe dac biet dl<br />
cd dugc tinh chat tir tinh mong mudn, chang han de chi tao van spin cd tir dien trd khdng Id<br />
(Giant Magnetoresistive - GMR), vat lieu mang mdng GMR ddi hdi phai cd ciu triic nano<br />
<br />
196<br />
Hgi nghi Khoa hoc ky- niim 35 ndm Viin KH&CNVN- Hd Noi -10/2010<br />
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luan phien da ldp kim loai (hoac hgp kim) tir tfnh va khdng tir tfnh, tao ra tir dien tra biln<br />
thien phu thupc vao tir trudng bao hda H (that vay, khi H=0 thi RH=Romax ; cdn H tang tli; RH<br />
giam; hieu img MR la am va bang AR/Ro = (RH-RO)/RO, 7% khi dcu/dcuNiCo tang tir 0,8 -H<br />
1,0. Miu cd MR cao nhit A28 (Hinh 2) da dat dp biln thien MR kha Idn (7,2%) ngay d viing<br />
tir trudng bao hda thap (± 500 Oe), mdt yeu ciu thudng dat ra ddi vdi vat lieu sensor tir.<br />
Cac mau B dugc thuc hien tren co sd giir dcuNiCo= const (ty le tuang img vdi i2.t2 ~<br />
4,8mAs) tuong duong vdi miu A22 cd MR thip (2,7%), song dp day dcu dugc khdng cbl chi<br />
bang 1/2 ciia miu A22 (tuang ung ii.ti = 6mAs) va ty so dcu/dcuNiCo« 1,25 thi cd thi cai thien<br />
dp biln thien MR gin gip 2 lin (MR trung binh dat « 5,3%).<br />
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-15 -10 -,'i 0 5 10 15<br />
<br />
H (kOe)<br />
Hinh 2; MR cita mdu 28 Hinh 3; Chieu ddy da lap ciia n =50<br />
Cung theo hudng cai thien dp biln thien MR, cac mau C xuit phat tir A26 (MR = 3,65%)<br />
dugc thuc hien d dieu kien dcuNiCo = const (tuang img iz.tj = 7,2mAs) va dcu =const nhung<br />
bien thien ca i, va t, sao cho i,.t, = 12mA. Kit qua cho thiy anh hudng ciia biln thien MR<br />
phu thupc chieu day cua ldp phii tir dcu rit man cam vdi biln thien nhd ciia thdng sd xung kit<br />
tua ldp phi tir il, tl.<br />
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199<br />
Tiiu ban Khoa hoc vdt liiu ISBN: 978-604-913-011-<br />
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2. Mpt vdi phan tich cdu trdc<br />
Ket qua d tren cho thay viec lira chpn va td hgp cac thdng sd ma xung rd rang ddng vai trd<br />
quyet dinh den chat lugng ldp ma bao gdm thanh phan hda hpc, cau true pha, hinli thai hpc<br />
ciia ldp ma ... gdp phin hinh thanh ciu hinh tir khac nhau vdi nhiing hanh vi MR xac dinh.<br />
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Hinh 5: Phdn tich EDX diim ciia lap mg<br />
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<br />
2 0 (d e g )<br />
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Hinh 4; Anh AFM ciia lap mg CuNiCo/Cu<br />
Hinh 6; Phd XRD ciia hgp kim Ni8ICul9<br />
<br />
Phan tich ciu tnic ciia mau ma cho hieu ung MR cao nhat (> 7%o) cho ta mdt sd ket qua<br />
khai quat sau day:<br />
- Anh SEM chup cat ngang mau A28 (Hinh 3) cho thay chieu day mau vdi sd da ldp n =<br />
50 vao khoang 217nm tuong ung vdi chieu day ciia mdi da ldp khoang 4,3nm. Be mat mau<br />
phang ban nhieu so vdi be mat de Si chiing td trong dieu kien ma xung kha nang san bang be<br />
mat ciia ldp ma cao ngay ca khi ldp ma d kich tbudc nanomet. Phan tich bang AFM cho thay<br />
mang kit tua cd cau tnic hat dai dac trung ddng deu, kicb thude trung binh ~ 150nm (Hinh 4).<br />
- Phan tich thanh phan hda hpc ciia ldp ma bang EDX diem (Hinh 5) cho thay thanh phan<br />
dung dich ran gdm Co 15,5%), Ni 38,75%) va Cu 45,75%o, chiing td trong dieu kien xung ddng<br />
Co uu tien phdng dien so vdi Ni xet theo thanh phan dung dich ban dau [Co^"^] : [Ni^"^] = 0,41<br />
: 2,3, tuy nhien theo phan tich XRD (Hinh 6) hop kim hinh thanh uu tien la Cu81Nil9.<br />
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IV. Ket luan<br />
Ap dung phuang phap ma xung ddng cho phep tir mdt dung dich ma duy nhat chira Cu2+<br />
Ni , Co che tao mdt ldp phii da ldp CuNiCo/Cu (luan phien N = 50 lan, day ~ 217nm) cd<br />
cau true nano tren nen n-Si, dat hieu ung GMR cue dai > 1% d dieu kien bien thien tir trudng<br />
bao hda H = ± 5kOe.<br />
Cac gia tri GMR dat dugc bang phuong phap xung dien hda budc dau cd the so sanh dugc<br />
vdi chit lugng cua cac ldp phu dugc che tao bang cac phuang phap vat ly dat tien (nhu PVD)<br />
dugc thuc hien trong dieu kien thuc nghiem kiem soat nghiem ngat, chirng td phuong phap<br />
ma xung dien hda la mdt ky thuat ma nano hieu qua cao. Viec lua chpn va td hgp cac thdng sd<br />
ma xung ciing nhu dieu chinh cac yeu td anh hudng dung dich be ma, cd the xem nhu la cac<br />
<br />
200<br />
Hoi nghi Khoa hgc ky niem 35 ndm Vien KH&CNVN - Hd Ngi -10/2010<br />
<br />
<br />
tien ich dieu khien qua trinh nguyen tir hda, tao kich thude hat, dinh hudng va phat trien sieu<br />
mang tir cau tnic nano gidng nhu muc tieu dugc tien hanh trong dieu kien lang dpng chan<br />
khdng bang phuong phap vat Iy.<br />
Loi cam on<br />
Tac gia xin cam on sir ho trg kinh phi tir de tai NCCB cap Nha nude ma sd 53.02.04 va dl<br />
tai KHCN cap Vien Khoa hpc va Cdng nghe Viet Nam (2006-2008) ciing nhu su giup da cua<br />
cac PTN cd tai ITIMS (DHBK Ha Ndi), Trung tam KHVL -DHQG Ha Ndi, Vien Khoa hoc<br />
Vat lieu (Vien KHCNVN).<br />
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TAI LIEU THAM KHAO<br />
1. a) P. Etienne, G. Creuzet, A. Friederich, F. Nguyen Van Dau, A. Fert, and J. Massies,<br />
Phys. Rev. Lett., 61, 2472 (1988).<br />
b) P. Grunberg, F. Saurenbach and W. Zinn, Phys. Rev. B, 39, p. 4828 (1989).<br />
2. W. Sehwarzacher, Electrochem. Soc. Interface,2
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