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Large magnetostrictive susceptibility in Tb–FeCo/FeCo multilayersN.. Teillet Citation: Applied Physics Letters 78, 3648 2001; doi: 10.1063/1.1354663 View online: http://dx.doi.org/10.106

Large magnetostrictive susceptibility in Tb–FeCo/FeCo multilayers

N H Duc, T M Danh, N A Tuan, and J Teillet

Citation: Applied Physics Letters 78, 3648 (2001); doi: 10.1063/1.1354663

View online: http://dx.doi.org/10.1063/1.1354663

View Table of Contents: http://scitation.aip.org/content/aip/journal/apl/78/23?ver=pdfcov

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Large magnetostrictive susceptibility in Tb–FeCo Õ FeCo multilayers

N H Duc,a)T M Danh, and N A Tuan

Cryogenic Laboratory, Faculty of Physics, Vietnam National University, Hanoi, 334 Nguyen Trai,

Thanh Xuan, Hanoi, Vietnam

J Teillet

GMP-UMR 6634, Universite´ de Rouen, 76821 Mont-saint-Aignan, France

共Received 2 November 2000; accepted for publication 18 January 2001兲

关Tb共Fe0.55Co0.45兲1.5/Fe兴n and 关Tb共Fe0.55Co0.45兲1.5/共Fe0.5Co0.5兴n multilayers were fabricated by

rf-magnetron sputtering from composite targets Magnetostriction was measured using an optical

deflectometer The as-deposited films showed a soft magnetic and magnetostrictive character, with

⫽1.4⫻10⫺2 T⫺1 This magnetostrictive softness was strongly improved by heat treatments: the

low-field dependence of the magnetostrictive susceptibility and their technical characters are

The need for microactuator applications did stimulate

the development of thin films with a large magnetostriction

and a large magnetostrictive susceptibility For single-layer

been achieved for TbFeCo/FeCo multilayers, which combine

layers with a large room-temperature magnetostriction and

of preparing this spring-magnet type magnetostrictive

关⫽K/2M s兴 by enhancing the average saturation

showing the possibility to control the orientation of the

the field dependence of the magnetostrictive susceptibilities

are still lacking in the literature

In this letter, we present results of our studies on

关Tb共Fe0.55Co0.45兲1.5/Fe0.5Co0.5兴n multilayers Attention is

fo-cused on the low-field magnetostrictive susceptibilities and

on the working point of magnetostrictive devices

The 关Tb共Fe0.55Co0.45兲1.5/Fe兴n and 关Tb共Fe0.55Co0.45兲1.5/

were prepared by rf-magnetron sputtering, with individual

power during sputtering was 400 W and the Ar pressure was

sub-strates were glass microscope cover slips with a nominal

water cooled Samples were annealed at temperatures from

to relieve any stress induced during the sputtering process

共Fe,Co兲 individual layers are crystalline, while the TbFeCo

is weakened and broadened due to the interdiffusion of

The magnetostriction was measured using an optical

bend-ing of the substrate due to the magnetostriction in the film

corre-spond to applied fields in the film plane, being parallel and perpendicular to the sample length, respectively For the films under investigation, the in-plane magnetostriction is

⫽0.7 T, the difference, ␭␥⫽␭储⫺␭⬜, was found to be about

multilayer, however is half of that of the single-layer film this is consistent with the fact that the magnetostriction of Fe

is negligible The parallel magnetostrictive hysteresis loops

a 兲Electronic mail: duc@cryolab.edu.vn

FIG 1 Parallel magnetostrictive hysteresis loops for the as-deposited

Tb 共Fe 0.55 Co 0.45 兲 2 single-layer 共1兲 and the Tb共Fe 0.55 Co 0.45 兲 1.5 /Fe multilayer

共2兲 films Definitions of magnetostriction remanence (␭r) and the coercive field ( ␮ 0 ␭H C) are illustrated for the Tb 共Fe 0.55 Co 0.45 兲 2 film.

APPLIED PHYSICS LETTERS VOLUME 78, NUMBER 23 4 JUNE 2001

3648

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single layer and the Tb共Fe0.55Co0.45兲1.5/Fe multilayer films.

In the as-deposited state, the low-field magnetostrictive

sus-ceptibility of the multilayer is observed to be higher than that

of the corresponding single-layer film, an expected

advan-tage of the spring-magnet type magnetostrictive multilayers

Annealing effects cause the saturation magnetostriction to

may be due to the interdiffusion of atoms between the layers,

which leads to the decrease of the rare-earth concentration

and, then, of the magnetostriction in the interface phases

1 nm more The development of the magnetostriction at low

fields after annealing, on the one hand, is caused by the

re-laxation of the amorphous TbFeCo phase as already

may be associated to the modification of the interfacial

com-position and structure This will be discussed in more detail

technical character of the magnetostriction and the

magneto-strictive susceptibility curves

Like in magnetic hysteresis loops, there is a so-called

⌬␭⫽␭s⫺␭(␭H C)⫽␭S The low-field dependence of the magnetostrictive

Tb共Fe0.55Co0.45兲1.5/Fe and Tb共Fe0.55Co0.45兲1.5/共Fe0.5Co0.5) multilayers, respectively As can be seen from these figures, the field direction dependence mentioned above may not be

For the annealed Tb共Fe0.55Co0.45兲1.5/Fe multilayer,␹␭储shows

共Fe0.5Co0.5兲 multilayer shows even a rather small and broad

⫻10⫺2 T⫺1 only兲 in magnetizing fields In demagnetizing

magnetostric-tive susceptibility maximum in demagnetizing fields could

be considered as a good working point for the magnetostric-tive films in microsystems

In conclusion, annealing effects enhance the magneto-strictive susceptibility of the TbFeCo/Fe,Co multilayers in

FIG 2 Parallel magnetostrictive hysteresis loops for the

Tb 共Fe 0.55 Co 0.45 兲 1.5 /Fe 共a兲 and the Tb共Fe 0.55 Co 0.45 兲 1.5 / 共Fe 0.5 Co 0.5 兲 共b兲

multi-layers: curves 共1兲 as-deposited, curves 共2兲 annealed multilayers.

FIG 3 Low-field dependence of the parallel magnetostrictive susceptibility for the Tb 共Fe 0.55 Co 0.45 兲 1.5 /Fe 共a兲 and the Tb共Fe 0.55 Co 0.45 兲 1.5 / 共Fe 0.5 Co 0.5 兲 共b兲

multilayers: curves 共1兲 as-deposited, curves 共2兲 annealed multilayers.

3649

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both low magnetizing and demagnetizing 共reverse兲 fields.

For applications, however, the magnetostrictive

susceptibil-ity enhancement in demagnetizing fields seems to be much

more useful and effective, in particular for dynamic modes

For the samples under investigation, by applying a bias

⬇6 mT), a magnetostriction change ⌬␭⬇10⫺4can be

ob-tained in an ac field of the magnitude of 2 mT

This work was supported by the Vietnam National

Uni-versity, Hanoi within Project QG.99.08 The assistance of

Nguyen Thi Ngoc Anh and Vu Nguyen Thuc in performing

magnetostriction measurements is gratefully acknowledged

The stay of N H Duc at the GMP, University of Rouen is

supported by the Ministe`re Francaise de l’Education

Nation-ale, de la Recherche et la Technologie

1E Quandt, J Alloys Compd 258, 126共1997兲.

2N H Duc, K Mackay, J Betz, and D Givord, J Appl Phys 79, 973

共1996兲.

3

F Schatz, M Hirscher, M Schnell, G Flik, and H Kronmu¨ller, J Appl.

Phys 76, 5380共1994兲.

4T M Danh, N H Duc, H N Thanh, and J Teillet, J Appl Phys 87,

5 N H Duc, T M Danh, H N Thanh, J Teillet, and A Lienard, J Phys.:

Condens Matter 12, 8283共2000兲.

6 S H Lim, Y S Choi, S H Han, H J Kim, T Shima, and H Fujimori, J.

Magn Magn Mater 189, 1共1998兲.

7 E Quandt, A Ludwig, J Betz, K Mackay, and D Givord, J Appl Phys.

81, 5420共1997兲.

8

P Farber and H Kronmu¨ller, J Appl Phys 88, 2781共2000兲.

9A Ludwig and E Quandt, J Appl Phys 87, 4691共2000兲.

10 E Tre´molet de Lacheisserise, K Mackey, J Betz, and J C Peuzin, J.

Alloys Compd 275-277, 685共1998兲.

11

N H Duc, T M Danh, N A Tuan, and J Teillet 共unpublished兲.

12E Tre´molet de Lacheisserise, Magnetostriction: Theory and Application

of Magnetoelasticity 共CRC, Boca Raton, FL, 1993兲, and references therein.

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