DAI HOC
QUCC
GIA
HA
NOI
TrUdng
Dai hoc Khoa hoc
TiT
nhicn

* ^
1^
^
i.

TEN DE
TAI
^ ^ - -'
OIEU KHIEN
CONG NGHE CHE TAG VA NGHIEN
CUU
CA(
CO CHE
TO
GIAG,
TO
TR6.
Dj HUONG
TU
VUONG
GOG

TPd.
DJ
HU6NG
TD
VUONG GOC
*
TRONG CAC MANG MONG Terfecohan
MA so
QG. 02-06
PT//f^4
-J
CHUTRlDgTAl:
PGS.TS.
NGUYIN
HOU
OLTC
CAC CAN BO
PHOI
HOP
THlTC HlfiN
1.
NCS.
D6
Thi Huong Giang
2.
CN. Vu Nguyen
Thurc
3.
NCS.
Nguyen

Khoa Vat ly, DHKHTN, DHQGHN
Khoa Cong nghe, DHQGHN
Khoa Cong nghe, DHQGHN
HA
NOI
-
2003
I. BAO CAO TOM TAT
1.
TflND^TAI:
"Dieu khien cong nghe che tao
vd
nghien
cihi
cdc
ccf
che
ti(
gido,
tif
trd,
di
hu&ng
tit vuong goc trong cdc mdng mong Terfecohan "
2.
MASd:
QG.02-06
3.
CHUTRID^TAI
PGS. TS. Nguyin

Khoa Vat ly, DHKHTN, DHQGHN
Khoa Cong nghe Thong tin,
DHQGHN
Khoa Cong nghe Thong tin, DHQGHN
5. MUC
Tl£U
VA NOI DUNG
NGHlfiN
CUU:
5.1.
Muc tieu nghien
cihi
cua de tai
- Nghien
ciiu cc
che' vat ly, ndng cao tinh chat
tit
gido,
tvt
tra vd khd ndng ghi
tH
quang cua vat lieu
- Tim kiem cdc
I
inh chat
tilt
nun
- Che
tqo duc/c
cdc vdt lieu co khd ndng

tvt
trd cua cdc mang mong da
l&p chi(a
TerfecoHan
-
Ngi dung
3: Tang
cudng
do
l&n
cua di
htccnxg tit
vuong goc va luc khdng tit
trong cdc mdng mong TerfecoHan
6. CAC
Kl^T QUA
DAT
DirOC:
6.1.
Ket qua nghien
curu:
7.
Da che' tao thanh cong cdc mang mong tit dua tren hop chat
TerfercoHan:
cdc mang dan
l&p
TerfecoHan, da
l&p
TerfecoHanlYFe,
TerfecoHanlYFeCo

fru'&ng
cao
(/.ijl
> 0,6 T)
/1
J.
3.
Trong cdc mdng mong ba
l&p
(sandwich) FelTerfecoHanlFe
v&i
chieu day
l&f)
Fe
(tfrj
tit 5 nm den 20
nm,
momen tit cua cdc
l&i?
Fe nam trong mat
phdng mdng nhung momen tit cua cdc l&p TerfecoHan lech ra khoi mat
phdng mdng. Cd'u
true
tit nhu
vqy
cho phep gid thiet su ton tai cua mot cau
true
domen dang
90"^
a

di
hu&ng
tit vuong goc fqi phdt trien mqnh tren
cdc mdng mong ba
hrj).
Ngodi ra
lite
khdng tit vuong goc con dqt duac
t&i
gid
^t'i
(MJ^C
^ 500
mT). Cdc thong
sdndy
thod man dieu kien ung dung cho ghi
tit vuong goc.
Ve
mat vdt
ly,
ca che luc khdng
tvt
vuong goc cao nay da duac
gidi thich bang
sU
hinh thanh
cdu
true nano trong
l&p
Fe a tren he mat. Ket

ngodi, cdu
true
tit ddi thanh song song
v&i
dien tra be. Do
Id
khd ndng tiem an cua mot cdu hinh tit - dien trd
m&i.
Tuy nhien, trong cdc vat lieu dang xet, do cdc dien
tu4fc6
do
linh
dgng thdp,
nen he so tit - dien trd quan sdt duac co gid tri be. Cdc nghien citu trong cdc
vdt lieu
CO
ndng do ddt hiem thdp han la rdt cdn thiet de khang dinh gid thiet
do [4,5].
6. Cdc nghien cuu cdu
true
vi mo, tinh chdt tit, tit gido vd ca che
tie
mem trong
cdc mdng mong da
l&p
TerfecoHanlYFe vd TerfecoHanlYFeCo la mot ket
qud vuat ra ngodi khuon kho da dang ki cua de tdi nhung co y
nghia
rdt ddc
biet [6,9]. Trong cdc nghien

v&i
gid tri cua cdc vdt lieu
Terfenol-D
quen thugc. Cdc ket qud
da dugc mo td dua tren cdu
true
tinh the gidn doqn trong cdc
hrj? Y(Fe,Co)
16-9].
7.
Vdt lieu tit gido che tqo duac da duac
sit
dung de che tqo sensa do tit
tru&ng
dua tren hieu
itng
tit gido - dp dien. Cung voi mot bo khuyech dqi dien tich tu
che'tqo,
sensa tit gido dp dien co the
sit
dung de dd
tittrit&ng.
6.2. Cac cong
trinh
khoa hoc da cong bo:
10 cong
trinh
dd cong bd tren cdc tap chi Khoa hoc vd cdc Hoi nghi Khoa
hoc trong
nii&c

Richomme
Presented in the International Conference on Magnetism, Rome
2003,
to be
published in J. Magn. Magn. Mater., 2004
4. Spintronics dua tren tren hieu itng tit - dien tra
du&ng
ngdm vd khd ndng
irng
dung
Nguyin Hull
Due
Tuyen t$p Hoi nghi Khoa hoc va Cong nghe Nano, Ha Noi, 5/2003, tr. 48.
5.
Dieu khien cdu
trdc
vi mo vd cdu
true
tit cua cdc mdng mong co cdu
trdc
nano nhdn tqo dqng
l&p
ddt hiem - kim
loqi
chuyen tiep
Nguyen HOii Dire
Se in trong: Tuyen tap Hoi
nghi
Vdt ly Chdt ran todn qudc
Idn tint

D6 Thi
Hircng
Giang,
Nguyin Hun
Dire,
Vu Nguyen
ThiJc
Se in trong: Tuyen tap Hoi nghi Vdt ly Chdt ran todn qudc
Ian tint
IV,
Niii
Coc
5-7/11/2003.
9. Natural nanostructure and magnetization reversal process in
TbFeColYJFeCo)j.j,
spring - magnets type multilayers
N.H.
Due, D.T. Huong Giang and
N.
Chau
Presented at the International Symposium on Advanced Magnetic Technology,
Taipei
2003,
to be published in J. Magn. Magn. Mater., 2004.
10.
Sensa do tit
tru&ng
dua tren hieu
itng
tit gido - dp dien

6.3.3.
Cii
nhdn: 06
-
va
Nguyen Thitc Khoa Vdt ly, DHKHTN, DHQGHN
Nguyen
Thanh Hdi
Nguyen Thi Minh Hong
Nguyen
Thanh Trung
Dqng Thi Minh Hong
va
Ditc Hung
Khoa Vdt ly, DHKHTN, DHQGHN
Khoa Vdt ly, DHKHTN, DHQGHN
Khoa Vdt ly, DHKHTN, DHQGHN
Khoa Vat ly, DHKHTN, DHQGHN
Khoa Cong nghe, DHQGH
6.3.4.
Sinh vien nghien
cihi
khoa hoc:
Da
hiring dan
05 sinh vien nghien cuu khoa hoc, trong do:
-
01
sinh vien dqt gidi nhi cap Bo GD&DT nam 2002
-

PGS.TS. Nguyin
HUu Dice
XAC NHAN CUA
TRUING
IL
SUMMARY OF THE REPORT
1.
TITLE OF THE PROJECT:
''Control
preparation technologies and study mechanisms of magnetostriction,
magnetoresistance and perpendicular anisotropy in TerfecoHan - based
films'*
2.
CODE OF THE PROJECT:
QG. 02-06
3.
DIRECTOR OF THE PROJECT:
Assoc.
Prof.
Dr. Nguyen Huu
Due
4.
PARTICIPANTS IN THE PROJECT:
7.
PhD. Student Do Thi Huong Giang
2.
BSc. Vu
Nguyen
Thuc
3.

Departement of Physics, HUS, VNU
Departement of Physics, HUS, VNU
Faculty of Technology, VNU
Faculty of Technology, VNU
8
5.2.
Contents:
- Study mechanism of giant magnetostriction in TerfecoHan-based films
with perpendicular anisotropy
- Study magnetoresistive properties of multilayer thin films based on
TerfecoHan
- Improve the strength of anisotropy and coercivity force in
TerfecoHan-based films
6.
OBTAINED
RERULTS:
6.1.
Scientific results :
7.
Magnetic films based on TerfecoHan compound consisting of TerfecoHan
single layer films, multilayer TerfecoHanlYFe and TerfecoHanlYFeCo films
and three-layer (sandwich)
FelTerfecoHanlFe
films have been successfully
prepared by using RF-magnetron sputtering machine in Center of Materials
Science, Department of Physics, Hanoi College of Science, VNU.
2.
Single layer TerfecoHan films exhibit a perpendicular anisotropy. The
magnetisation process in these thin films can be described by the rotation of
magnetic moments from

order
to release stress induced in the preparation), the
magnetostrictive susceptibility
Xxii ^
2,5xlO'^T^
has been obtained in these
sandwiches. This value is larger than that of single layer TerfecoHan films
HI.
4. The perpendicular anisotropy has been developed significantly in these
three-layer FelTerfecoHanlFe films after annealed at temperature
T^
> 250
TT.
In addition, the perpendicular coercivity force reached to a value as
large as 500 mT. These investigated films with perpendicular anisotropy and
high coercivity are very promising for perpendicular magnetic recording
materials. The mechanism of high perpendicular coercivity has been
explained by the nanostructural formation of the upper Fe-layer. These
results have been verified by studies in transmission electron microscope
images.
5. The magnetoresistance effects in mutilayer thin films TerfecoHanlYFe and
TerfecoHanlYFeCo have been investigated. These films exhibit a
magnetoresistance ratio MR of 0,2% only. It can be supposed that the
perpendicular magnetization configuration in these mutilayers supports a
large resistance state. In applied magnetic fields, the change into parallel
magnetization configuration leads to a small resistance state. Thus, it is able
to propose a new magnetoresistance configuration. The low MR value
observed in the investigated multilayers results from low polarisation of
electrons 4f Further studies in materials with lower concentration of rare
earth will he necessary to confirm this proposal [4,5].

effects. Combining with a
home-made electronic amplifier, sensor can be used for detecting magnetic
fields.
6.2. Publications :
7.
Magnetisation process and magnetostriction in FelTerfecohanlFe
sandwich films with perpendicular
N.H.
Due,
V.N. Thuc, D.T. Huong Giang,
N.T.
Minh Hong and N.
Qiau
Physica B327 (2003) 328.
2.
Magnetisation process in FelTerfecohanlFe sandwich films
D.T. Huong Giang,
N.T.
Tmng and
N.H.
Due
VNU. Joumal of Science, Mathematics - Physics,
2003.
3.
Magnetisation and magnetostriction in FelTerfecohanlFe sandwich films
with an extended domain wall formation
N.H.
Due,
D.T. Huong Giang, V.N.
Tliuc,

TerfecohanlYFeCo multilayers
D.T.
Huong Giang,
N.H.
Due,
F.
Richommer and
S.
Schulze
J. Magn. Magn. Mater., 262 (2003) 361.
7.
Nanostructure and magnetic softness of magnetostrictive
{TerfecohanlYFeCo} multilayers
D.T. Huong Giang,
N.H.
Due,
F.
Richommer,
N.T.
Hien and
S.
Schulze
Proceedings of The Sixth German - Vietnamese Seminar on Physics and
Engineering, Chemnitz, Germany, 25 May - 31 May,
2003.
8. Vat lieu
ti(
gido kieu spring - magnet TerfecohanlYFeCo
D6 Thi Huang Giang, Nguyin Huu
Dire,

Se in trong: Tuyen tap Hoi
nghi Vdt
ly Chdt ran todn qudc
Idn thit
IV,
Nui
Coc
5-7/11/2003.
6.3.
Training results :
6.3.1.
PhD:
01
- Do Thi Huong Giang (in progress)
6.3.2.
Master: 01
- Vu Nguyen Thuc (in progress)
6.3.3. Bachelor: 06
12
- Vu Nguyen Thuc Departement of Physics, HUS, VNU
- Nguyen Thanh Hai Departement of Physics, HUS,
VNU
- Nguyen Thi Minh Hong Departement of Physics, HUS,
\ ^NU
- Nguyen Thanh Trung Departement of Physics,
HUS,
VNU
- Dang Thi Minh Hong Departement of Physics, HUS,
\ 'NU
- Vu Due Hung Faculty of Technology, VNU

citu
18
3.
Ketlu$n
23
Tai lieu tham khao 26
Phuluc
27
Phi^'u ddng
ky ket qua
nghien
curu
1.
LOI
MO DAU
vat
lieu
tir
giao (cung nhu cac vat lieu ap dien khac) la cac vat lieu co kha
nang bien doi dien nang thanh ca nang.
Chiing thudng
duac su dung de che tao cac
cam bien, bo phan truyen dong, bo phan dich chuyen cung nhu cac thiet bi dien-ca
khac.
Trong s6 cac vat
li6u
tir giao dang duac nghien curu hien nay, vat lieu
tijf
giao
dang mang mong dang gay duac su quan tarn

sir
dung
hieu ling tijr
giao, cac mang mong phai co iii giao cao trong viing
tijr truofng
tha'p,
tiic
la do cam
tir
giao
Idn (xx = dX[d{[ioH)
>
2x10^
T')
va
lire
khang
t\x
nho
(MOHC
« 100 mT) [4]. Cac cd gang lam giam
tir trucfng
dieu khien doi vai cac vat
lidu tijr
giao da duac
tie'n
hanh theo
nhilu each
khac nhau. Theo
truyin

djnh
hinh.
Tuy nhien, trong trang thai nay, cac hap chat
a-Terfenol
va
a-Terfenol-D
co
ca'u triic
speri
tir,
trong do momen
tir ciia
Tb phan bd trong mot goc
con rong.
Chinh
dieu nay lam giam nhiet do Curie
(Tc =
410 K v6i hop kim
v6
dinh
hinh
a-Terfenol) va do do lam giam
tir
giao
d
nhiet do phong.
Cung
vdi
muc
dich

tdn
tai nhu da
quan sat
tha'y
ddi vdi cac hgp kim
a-TerfenoI,
nhung
vi
tir
tinh
cua phan mang Co
dugc tang cudng (do hieu
ling
the
tfch) nen
nhiet do Curie da tang
len
gan 600 K [1].
Nguyen nhan ca ban lam giam tir giao cua cac hgp chat
a-TbFe2
va
a-TbCoj
so
vdi cac hgp kim tinh the la do ca'u triic speri tir
ctia
phan mang
daft
hiem. De tang tir
giao trong cac hgp chat nay can phai giam gdc con cua cac momen tir trong phan
15

lam giam anh hudng
ciia
Dy, cac hgp
chat vd dinh
hinh
cd ndng dp Tb cao ban
la
a-Tb(Feo,5sCO()45),
5 (tii'c
la TerfecoHan)
da dugc che tao
vji
nghien cuu thanh cong tai bo
mdn
Vat ly Nhiet dp tha'p bdi nhdm
tac gia Nguyin
Hun Due
va cac cong
sir
[8,9].
6
day, Ter cd
nghla
la
Tb,/^
la Fe,
CO
la Co va Han la ten viet tat ciia Ha Noi. Cac hgp
ch^t
nay hien nay van dang

cd dp tir hoa
Idn
(FeCo)
thudng dugc quan tam [10-12]. Y tudng nay
hinh
thanh tir mdi lien he giua tir dp
bao hoa
Ms
va tir trudng bao boa
H^.
Thay
vi
giam hang sd di hudng
K^
(=
/jJ4^^)
nhu cac
each
tiep
can
trudc day, su to hgp nay
vdn
dam bao vat lieu cd tir giao
Idn
ddng thdi giam dugc tir trudng bao hoa
H^
do dp tir boa trung
blnh
M^
dugc tang

nhieu cho cac qua trinh dao tir so vdi cdu triic dong nha't (tinh the hoac vd dinh
16
hinh).
Dd
la
cdu
hinh
tdi uu cho cac vat lieu tir to hgp de nang cao dac
tinh
tir mem
ciia cac vat lieu tir to hgp. Theo truyin thdng, cdu triic
nand
dang hat thudng dugc
hinh thanh tir trang
thai
vd dinh
hinh
ban ddu nhd cac qua trinh
xir
ly nhiet [5]. Cac
nghien
cihi
cua Quandt va cac ddng nghiep da
chi
ra rang, trang thai nano cd the
hinh
thanh
mdt each
tu nhien trong
Idp

va tir gao cao, dap
ling yeu cdu ung dung, cac mang ba
Idp
(sandwich) Fe/TerfecoHan/Fe vdi sd chu ky
nhd cung da dugc
che
tao va nghien cuu. Qua trinh tir boa va ca che
hinh
thanh vach
dd men cung da dugc thao
luan.
.
' '•)
2.
NOI DUNG vA
K£T
QUA
NGHII&N
CUU
2.1.
Cac phuang phap
thirc
nghiem
Cac he mang mdng da
Idp
Terfecoban/Yj^Fe,.^
va
Terfecohan/Yx(Fen,7Coo,3)i.x
{x = 0; 0,1 va 0,2) cd so chu ki n = 50 vdi
chilu

mbar, thdi gian
Ih
tai cac nhiet do khac nhau tai Bp mdn Vat ly Nhiet dd Thdp,
Khoa vat ly, Trudng Dai hpc Khoa hpc Tu Nhien.
17
Cdu triic vi mo
ciia
mdu dugc xac dinh thdng qua phep do
phd
nhilu xa tia X
tai Bp mdn Vat ly Ghat
rdn,
Khoa Vat ly, Dai hpc Khoa hpc Tu nhien va anh chup
hi^n
vi dien tir truyin qua dp phan giai cao (HR-TEM) tai Trudng Dai hpc Tong hpp
Chemnitz, CHLB Due.
Cac
tinh
chdt tir
ciia
mdu dugc khao sat bang phep do dudng cong tir
tri
tren he
do tir ke mdu rung (VSM) dugc thuc hien tai Trung tam Khoa hpc Vat lieu, Trudng
Dai hpc Khoa hpc Tu nhien va Trung tam
ITIMS,
Trudng Dai hpc Bach khoa Ha
Ndi.
Cac nghien
ciiu tinh

Idn
A
= 1080x10 "^
nhung bao
hoa d tir trudng cao
JL/^H
> 0,6
T (xem hinh 1) [1]. Gia tri tir
giao dat dugc vdn giu ky luc
Idn
nha't so vdi cac ket qua dat
dugc tren cac vat lieu tir giao
dang mang dugc nghien
cioi
tren the' gidi cho den nay. Cac
mang sau khi
ii
nhiet, di hudng
tir chuyen tir phuang vuong gdc
sang phuang song song vdi mat
phang mang. Qua trinh u nhiet
cd tac dung
khir
ung sudt va
1200
1000
800
o
^
600

tinh
tir
mIm
tren cdc mang nghien
ciiii
(xem phu luc kem theo).
2.2.b.
Mdng ba
Idp
(sandwich) FelTerfecoHanlFe
Cac mang mdng 3
Idp
(sandwich)
Fe/TerfecoHan/Fe vdi chilu day
Idp
Fe thay
doi
/pe
= 5, 10, 15, 20, 25, 40, 60 va 90 nm
(ki
hieu S5,
SIO,
S20, S25, S40, S60 va S90
tuang ling) da
dude
che' tao. Cac nghien
ciiu
vl cdu triic vi md,
tinh
chdt tir va tir giao da

^ ^ , , , ciia cdc mang
ba
Idp FelTerfecohanlFe
hoa va thuc day qua trinh quay xay ra
tai
tu
ngay sau khi che tqo
trudng thdp ban va
lii
giao phat trien nhanh d
tir trudng thdp. Cac mdu ba
Idp
khi u d nhiet
dd
T^A
^
250
°C
(de khir
ling
sudt) cho
dp cam tir giao
j^//
'^
2,5xlO^T'.
Gia tri nay
Idn
ban gia tri thu dugc tren cac mang
mdng dan Idp
[1].

phang nhanh chdng dugc thiet lap.
Sir
khac nhau vl dp Idn
ciia lire
khang tir
giija
cac
lap trong trudng hgp nay ddn den qua trinh dao tir khac nhau trong cac
Idp
va do dd
19
ddn den su
hinh
thanh cdu triic ddmen dang 180° trong viing chuyen tiep.
Sir
hinh
thanh vach ddmen trong viing chuyen tie'p giua cac Idp vat lieu gay
nen
cac
tinh
chdt
tir va tir giao
Ii
thii.
Cac ket qua dua tren nhtrng phep do tir dp va tir giao se cho phep
nhan biet mdt
each
gian tiep su xudt hien cua vach ddmen tren cac he mang mdng
ba
Idp

Hinh
3.
Dudng
cong
tir
tri
do theo phuang song song (II)
va
vuong goc
(1)
ciia
cac
mdng ba lap
FelTerfecohanlFe
sau khi
ii
d
nhiet
do
T^
=
450
TT
2.2.C,
Mdng da
lap
TerfecoHonlY^Fcj.^
vd
TerfecoHanlYJFeCo)^,^
Cac mang da

Yo,,(FeCo)n,9 (hinh
4b) va vd dinh hinh vdi
Y().2(FeCo)(,
R
(hinh 4a).
K^t
qua nay md ra kha nang che tao cac
Idp
nand tinh the
YFeCo trong mang da
Idp
{a-Terfecohan/n-YFeCo) bang
each
dilu chinh ndng dp
Y dl thu dugc cac
tinh
chdt tir
mIm
va tir giao tdt.
(a) (b)
Hinh
4,
Gidn
do nhiiu
xg tia Xciia cdc mang
TerfecohanlYJ^e,,^
ngay sau
khi che tao (a) va
dnh
chup hien

T' thu dugc tren cac
mang
{Terfecohan/Yo
iFeogj^
va
{TerfecoHan/Yo,(FeCo)o9)n
tuang
ling
(hinh 5)
Gia tri dd cam tir giao thu dugc tren cac mang nay
Idn
ban mot bac do
Idn
so vdi gia
tri dp cam tir giao tren mang dan
Idp
TerfecoHan da cong bd.
Cac nghien
ciiu
vl
linh
chdt tir - dien trd cung da dugc
ti^n
hanh tren bai he
mdu nay. Ket qua nghien
ciai
cho thdy he sd tir dien trd GMR cd gia tri nhd MR =
0,25%
va cd qui
luat

1
•
r—
'
a
I
ONJK
§
'
-
(b)
_
1.1.
-40
-20 0 20
u
H (mT)
40 60
-60
-40
-20
0 20
u
H (mT)
40 60
Hinh
5.
Dudng cong tit gido tong cong
(a)
vd

nghi khoa hpc trong
dd
01
bai
bao dang tren
tap
chi
Qudc
td
vl
Tir hpc va Vat
lieu
tir (J.
Magn. Magn. Mater., North-
Holland, 2003)
va 01 bao cao
tai Hdi nghi Qudc te'
vl Vat ly
va Ky thuat (CHLB
Diic,
2003)
(xem phu luc kem theo).
0.00
-0.05
-0.10
^
-0.15
-0.20
-0.25
CDD

!
2.2.d.
Nghien
citu
itng dung
vat lieu
tir
giao dang mang mdng TerfecoHan
da
dugc nghien
cihi
ling dung
trong viec che tao sensa do
tir
trudng dua tren hieu
ling
tu
giao
- ap
dien. Sir dung
vat lieu ap dien dang tdm APC
-
855 (American Piezoceramics Inc., PA, USA cung
cdp),
sensa boat ddng nhd
sir kdt
hgp giua hieu
ling
tir giao xudt hien dudi tac dung
cua

ra
tren
hai
cue
cua tdm
vat
lieu
ap
dien dugc thuc hien
22
nhd mdt mach khuyech dai cdng cu tu che' tao vdi he sd khuyech dai bang 1,5.
Kdt
qua nghien
cihi
cho thdy sensa cho dp nhay kha tdt vdi cac mang tir giao cd dd day
2-5
|im.
Ddi vdi cac mang mdng tir giao chua u nhiet cd dp day 5
|.im
va dien tich
5x20
mm^
sensa dat he sd dien - tir dU/dH
-
8 V/T trong vung
tii'
trudng
//// ~
0.1
T

mili Tesla)
cho phep sensa
cd kha nang sir dung lam thiet bi dd va phat hien tir trudng rat
hiJu
hieu.
Kdt
qua nay
r^t
kha quan ddi vdi viec trien khai
ling
dung trong thuc
tiln.
^
1.5 -
7
i:
5
4
T3
0.0
•
r
'•
—1
'
1
'
1
•
1

K^
(T)
0.6
Hinh
7.
Dudng cong suthay
doi
ciia the
dp
dien Idi
ra (a) vd he sd dien - tir(b)
theo
tit
trudng ngodi ciia
sensa
3.
KfiT
LUAN
1.
Da che' tao thanh cdng cac mang mdng tir dua tren hgp chdt TerfercoHan:
cac mang dan Idp TerfecoHan, da
Idp
TerfecoHan/YFe, TerfecoHan/YFeCo
va ba
Idp
Fe/TerfecoHan/Fe tren thiet bi
phiin
xa catdt tai Trung tam Khoa
hpc Vat lieu, Khoa Vat ly, Dai hpc Khoa hpc Tu nhien, Dai hpc Qudc gia
Ha

vay
cho phep gia thiet su tdn tai cua mdt cdu
triic ddmen dang
90*^
d cac interfaces. Dd ciing la nguyen nhan lam giam tir
trudng bao boa va
thiic
d^y
qua trinh quay xay ra tai tir trudng thdp ban va
tir giao phat
triln
nhanh d tir trudng thdp. Cac mdu ba
Idp
khi
ii
d nhiet dp
TA
< 250
°C
(de khir
ling
sudt) cho dp cam tir giao
Xx//
-
2,5xlO^T*.
Gia tri
nay
Idn
ban gia tri thu dugc tren cac mang mdng dan
Idp.

iu
- dien trd tren cac mang da
Idp
TerfecoHan/YFe va
TerfecoHan/YFeCo da dugc khao sat. Dudng cong tir
tri
R(H) cd dang
gidng nhu dudng cong tir giao
X(H),
tuy nhien, he sd tir - dien trd
chi
dat cue
dai MR = 0,2%. Ket qua nay cho phep nhan xet
rdng,
cdu
hinh
tir dp vuong
gdc trong cac mang mdng da
Idp
cd the dugc xem xet nhu la cau hinh
ciia
dien trd
Idn.
Dudi tac dung cua tir trudng ngoai, cdu triic tir ddi thanh song
song vdi dien trd be. Do la kha nang
tilm dn
cua
mgt
cdu hinh tir - dien trd
mdi.