.

∗

Corresponding

author.

Tel.:

+84

4

3754

9665;

fax:

+84

4

3754

7460.

E-mail

address:

[email protected]

(D.T.H.

Giang).

Regarding

the

high

magnetoelectric

voltage

coefficients,

mul-

tiferroic

composites

on

the

basis

of

magnetostrictive

ferrites

and

rare

earth-transition

intermetallics

have

been

studied

intensively

since

the

beginning

of

this

century

[2,3,5–10]

.

In

particular,

opera-

tion

principle,

design

and

functioning

characteristics

of

these

new

ME

sensors

have

also

been

described

[2,3]

.

Values

of

magnetic

field

response

(

dV

ME

/

dH

)

as

high

as

0.06

×

10

−

3

V/Oe,

56

×

10

−

3

V/Oe

and

13

×

10

−

3

V/Oe

were

reported

for

ME

sensors

using

magne-

tostrictive

Ni

0.5

Zn

0.5

Fe

2

O

3

ferrites

[5]

,

Terfenol-D

laminates

[6]

and

Terfecohan

thin

films

[7]

,

respectively.

In

an

approach

to

use

ME

sensors

for

the

determination

of

ac

magnetic-field

strengths,

Fetisov

et

al.

[8]

have

successfully

developed

a

promising

sensor

with

a

sensitivity

better

than

10

−

3

Oe

for

milli-Hz

frequency

mag-

netic

fields.

Furthermore,

strong

efforts

have

been

undertaken

to

enhance

the

ME

effects

by

altering

the

shape

and

the

volume

ratio

of

the

piezoelectric/magnetostrictive

laminates

[11]

or

by

improving

the

lamination

process

[12]

.

In

the

case

of

micro

fabrication,

Greve

et

al.

[13]

reported

a

giant

ME

coefficient

as

high

as

737

V/cm

Oe

for

(Fe

90

Co

10

)

78

Si

12

B

10

-AlN

thin

film

composites.

Recently,

an

ME

sensor

using

Co-based

Metglas/PZT

laminates

was

designed,

fab-

ricated

and

characterized

for

determining

the

strengths

as

well

as

the

orientations

of

dc

-

and

ac

-magnetic

fields

[3]

,

where

an

ME-

voltage

response

(

dV

ME

/

dH

)

of

2

×

10

−

3

V/Oe

at

low

dc

fields

and,

in

particular,

a

response

(

dV

ME

/

dh

ac

)

as

high

as

17

×

10

−

3

V/Oe

at

the

low

ac

-ones

was

reported.

These

findings

imply

a

great

potential

for

self-powered

detection

of

low

ac

-magnetic

fields.

For

an

optimal

design

of

ME

laminate

sensors,

modeling

approaches

have

been

undertaken

by

several

research

groups

(

e.g.

[14–20]

).

While

some

models

[15]

have

taken

into

account

the

effect

of

the

thickness

ratio

between

the

piezoelectric

and

0924-4247/$

–

see

front

matter

©

 2012 Elsevier B.V. All rights reserved.

doi:

10.1016/j.sna.2012.03.030