In luence o Co addi ion on he magne ocalo ic e ec o FeCoSiAlGaPCB
amo phous alloys
V. F anco, J. M. Bo ego, and A. Conde
Dp o. Física de la Ma e ia Condensada, ICMSE-CSIC, Uni e sidad de Se illa, P.O. Box 1065,
41080 Se illa, Spain
S. Ro h
Leibniz Ins i u ü Me allische We ks o e, IFW D esden, Pos ach 270016, D 01171 D esden, Ge many
共Recei ed 9 Janua y 2006; accep ed 22 Feb ua y 2006; published online 28 Ma ch 2006兲
The FeCoSiAlGaPCB alloys can be p epa ed as bulk amo phous ma e ials, wi h ou s anding
mechanical p ope ies and inc eased elec ical esis i i y. These ea u es can be bene icial o hei
applica ion as a magne ic e ige an . The in luence o Co addi ion on he magne ic en opy change
o he alloy has been s udied. This composi ional modi ica ion displaces he empe a u e o he peak
en opy change close o oom empe a u e, bu educes he e ige an capaci y o he ma e ial. Fo
he Co- ee alloy, he peak en opy change is inc eased wi h espec o a Fineme alloy con aining
Mo, bu i s e ige an capaci y is no enhanced. © 2006 Ame ican Ins i u e o Physics.
关DOI: 10.1063/1.2188385兴
Magne ic e ige a ion is a ield o esea ch ha has
gained inc easing a en ion, as i is conside ed an al e na i e
o he gas comp ession-expansion cycle. A empe a u es
close o oom empe a u e, a e-ea h-based ma e ials a e
among he mos ele an ones.1–4 To display a big magne o-
calo ic esponse, wo equi emen s ha e o be ul illed: he
ma e ial needs o exhibi a big magne ic momen and, also, a
s ong empe a u e dependence o magne iza ion close o he
wo king empe a u e. This second condi ion, ela ed o a
magne ic phase ansi ion, can be achie ed in wo di e en
ways. Ei he by a i s -o de phase ansi ion, which p oduces
an ab up empe a u e change o he magne ic momen and,
he e o e, a ema kable peak in he magne ic en opy change
共⌬SM兲a he ansi ion empe a u e, o by a second o de
phase ansi ion, which causes a mo e smea ed peak in ⌬SM.
Howe e , he ema kable hys e esis ha appea s in some ma-
e ials, associa ed o i s o de phase ansi ions, may educe
he ac ual e iciency o he cooling p ocess.5I has been
poin ed ou , ne e heless, ha in o de o compa e he cha -
ac e is ics o di e en ma e ials as candida es o magne ic
e ige an s, hei e ige an capaci y 共RC兲in a e e sible
cycle, connec ed o he en opy abso bed by he e ige an a
he cold end o he cycle and i s empe a u e span, should be
used.6
The sea ch o low-cos ma e ials o high- empe a u e
magne ic e ige a ion is a ield o cu en in e es .7–12 Re-
cen ly i has been shown ha some so -magne ic amo phous
alloys a e good candida es o his applica ion,11 wi h a e-
ige an capaci y ha is compa able o ha o low-hys e e ic
Gd-based ma e ials.4I has also been shown ha he nanoc-
ys alliza ion o he alloy, al hough b oadening he ⌬SM
peak, does no imp o e he RC o he ma e ial. Besides he
peak en opy change, RC and ma e ial cos , he e a e o he
ac o s ha should be aken in o accoun o a ma e ial o be
e icien ly applied,12 such as mechanical p ope ies, co o-
sion esis ance, elec ical esis i i y, e c.
Mul icomponen Fe-based bulk amo phous alloys, o-
ge he wi h hei p omising magne ic p ope ies,13,14 p esen
ou s anding mechanical p ope ies.13,15 Pieces o applica ion
de ices, wi h he inal equi ed shape, could be p epa ed by
mold cas ing. Fo he Fe–共Al, Ga兲–共P, C, B, Si兲alloy se ies,
cylinde s wi h up o 3 mm in diame e ha e been ob ained.13
Mo eo e , he high elec ical esis i i y associa ed o he
nonc ys alline cha ac e o he alloys is a bene icial ea u e
o hei applica ion as e ige an ma e ials. Howe e , he e
a e ew s udies conce ning he magne ocalo ic esponse o
bulk amo phous alloys.16 I has been shown ha he Co ad-
di ion o his amily o alloys p oduces a dec ease o i s
Cu ie empe a u e, TC
am.14 The e o e, his composi ional
change could be a way o uning he ⌬SMpeak empe a u e.
In his wo k he magne ic en opy change o he FeCoSiAl-
GaPCB se ies is cha ac e ized, analyzing he in luence o Co
addi ion on he e ige an capaci y o he ma e ial.
Amo phous ibbons, ⬃25
␮
m hick and ⬃10 mm wide,
wi h nominal composi ion 共FexCoyBzCu兲Si3Al5Ga2P10 共Table
I兲we e p epa ed by single- olle mel spinning. The amo -
phous cha ac e o he as-quenched alloys was checked by
x- ay di ac ion. P e iously o he measu emen s, samples
we e s ess elaxed by he mal annealing in an A a mo-
sphe e a 675 K o 30 min. The ield dependence o magne-
iza ion was measu ed in a Lakesho e 7407 Vib a ing Sample
Magne ome e using a maximum applied ield H=15 kOe
wi h ield s eps o 50 Oe, o cons an empe a u es in he
ange 300–720 K in inc emen s o 10 K. The magne ic en-
opy change due o he applica ion o a magne ic ield Hhas
been calcula ed om he nume ical app oxima ion o he
equa ion
TABLE I. Composi ion o he s udied 共FexCoyBzCu兲Si3Al5Ga2P10 alloys.
Alloy A B C D E F
x70 56 43 29 17 5
y01426405263
z5 6 8 9 10 12
u543210
APPLIED PHYSICS LETTERS 88, 132509 共2006兲
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⌬SM=
冕
0
H
冉
⳵
M
⳵
T
冊
H
dH,共1兲
whe e he pa ial de i a i e is eplaced by ini e di e ences
and he in eg a ion is pe o med nume ically.
Figu e 1 shows he empe a u e dependence o he mag-
ne ic en opy change co esponding o an applied ield H
=15 kOe o he di e en s udied samples. The e is a e-
ma kable co ela ion be ween he ⌬SMpeak empe a u es
共Tpk兲o each sample and i s co esponding TC
am calcula ed by
he “kink poin ” me hod 共Fig. 2兲. Al hough Tpk is shi ed o
empe a u es close o oom empe a u e as he Co con en in
he alloy inc eases, he magni ude o he peak 共兩⌬SM
pk兩兲 con-
inuously dec eases wi h inc easing Co con en 共Fig. 2兲. This
composi ional dependence o 兩⌬SM
pk兩is in ag eemen wi h he
con inuous dec ease o he magne ic momen pe ansi ion
me al a om as Co con en inc eases in his se ies o alloys.14
The RC o he samples has been calcula ed by he Wood
and Po e me hod6共⌬SM⌬Tin Fig. 3兲, ei he using he op-
imal cycle empe a u es o imposing oom empe a u e as
he empe a u e o he cold ese oi 共 he cold and ho ese -
oi empe a u es, Tcand Th, a e plo ed in Fig. 4 in bo h
cases兲. To allow he compa ison wi h published da a o
o he ma e ials, he p oduc o he peak en opy change imes
he ull wid h a hal maximum o he peak 共⌬SM
pk ⌬TFWHM in
Fig. 3兲, and he a ea unde he ⌬SM共T兲cu es using he
empe a u es a hal -maximum o he peak as he in eg a ion
limi s 共A ea in Fig. 3兲ha e also been calcula ed. Fo he
sample wi h he lowes Fe con en , he RC o he op imal
cycle could no be calcula ed, as he peak is oo close o
oom empe a u e and Tc共op imal兲is below he a ailable
expe imen al ange. As he Co con en inc eases, he RC o
he samples dec eases. The mino di e ences in ⌬SM⌬T o
he op imal cycle and o ha wi h Tca oom empe a u e
e idence ha he bes pe o mance o hese ma e ials is
achie ed o a cold ese oi close o oom empe a u e. Fig-
u e 4 shows he empe a u es o he op imal cycles and hose
o he cycles wi h Tca oom empe a u e. While Thdisplays
no big di e ences be ween bo h cycles, Tc共op imal兲p esen s
a mo e sca e ed cha ac e . This is ela ed o he ac ha he
low- empe a u e pa o he ⌬SM共Fig. 1兲has a smalle em-
pe a u e dependence and a mino change in he ⌬SM alue
co esponding o he selec ed empe a u es o he cycles im-
plies a ele an change in he associa ed empe a u e. As Co
con en inc eases, he empe a u e span o he cycles is
educed.
Al hough he Co addi ion in he FeCoSiAlGaPCB alloy
se ies can be used o ine une TC
am and, consequen ly, Tpk,i
dec eases bo h 兩⌬SM
pk兩and he RC o he ma e ial. The Co-
ee alloy p esen s a RC compa able o ha o a Mo-Fineme
alloy wi h a simila Fe con en ,11 al hough 兩⌬SM
pk兩and he
empe a u e span a e bigge in he p esen case.
FIG. 1. 共Colo online兲Tempe a u e dependence o he magne ic en opy
change o he di e en s udied alloys. Lines a e a guide o he eye.
FIG. 2. 共Colo online兲Composi ional dependence o he Cu ie empe a u e
o he alloys, he peak en opy change empe a u e, and he maximum mag-
ne ic en opy change. Lines a e a guide o he eye.
FIG. 3. 共Colo online兲Composi ional dependence o he e ige an capaci y
共RC兲calcula ed by h ee di e en me hods 共 o he Wood and Po e
me hod, RC has been calcula ed o he op imal e e sible e ige a ion
cycle and o cycles depa ing om oom empe a u e兲. Lines a e a guide o
he eye.
FIG. 4. 共Colo online兲Composi ional dependence o he empe a u es o he
cold and ho ese oi s o he op imal cycles 共solid symbols兲and o cycles
depa ing om oom empe a u e 共open symbols兲. Lines a e a guide o he
eye.
132509-2 F anco e al. Appl. Phys. Le . 88, 132509 共2006兲
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and EU-FEDER 共P ojec MAT 2004-04618兲and he PAI o
Jun a de Andalucía.
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