effect of niobium addition on the martensitic
TRANSCRIPT
Effect of niobium addition on the martensitic transformation and magnetocaloric effectin low hysteresis NiCoMnSn magnetic shape memory alloysBaris Emre, Nickolaus M. Bruno, Suheyla Yuce Emre, and Ibrahim Karaman Citation: Applied Physics Letters 105, 231910 (2014); doi: 10.1063/1.4903494 View online: http://dx.doi.org/10.1063/1.4903494 View Table of Contents: http://scitation.aip.org/content/aip/journal/apl/105/23?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Large reversible entropy change at the inverse magnetocaloric effect in Ni-Co-Mn-Ga-In magnetic shapememory alloys J. Appl. Phys. 113, 213905 (2013); 10.1063/1.4808340 Elastocaloric and magnetocaloric effects in Ni-Mn-Sn(Cu) shape-memory alloy J. Appl. Phys. 113, 053506 (2013); 10.1063/1.4790140 The martensitic transformation, magnetocaloric effect, and magnetoresistance in high-Mn content Mn 47 + x Ni43 − x Sn 10 ferromagnetic shape memory alloys J. Appl. Phys. 108, 103920 (2010); 10.1063/1.3511748 Mössbauer study on martensite phase in Ni 50 Mn 36.5 Fe 0.5 57 Sn 13 metamagnetic shape memory alloy Appl. Phys. Lett. 93, 042509 (2008); 10.1063/1.2960551 Boron’s effect on martensitic transformation and magnetocaloric effect in Ni 43 Mn 46 Sn 11 B x alloys Appl. Phys. Lett. 92, 102503 (2008); 10.1063/1.2895645
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
165.91.74.118 On: Wed, 02 Sep 2015 21:34:00
Effect of niobium addition on the martensitic transformationand magnetocaloric effect in low hysteresis NiCoMnSnmagnetic shape memory alloys
Baris Emre,1 Nickolaus M. Bruno,2 Suheyla Yuce Emre,3 and Ibrahim Karaman2,4,a)
1Department of Engineering Physics, Ankara University, 06100 Ankara, Turkey2Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843, USA3Department of Physics, Ondokuz Mayis University, 55139 Samsun, Turkey4Department of Materials Science and Engineering, Texas A&M University, College Station,Texas 77843, USA
(Received 25 October 2014; accepted 17 November 2014; published online 11 December 2014)
The effect of Nb substitution for Ni in Ni45Co5Mn40Sn10 magnetic shape memory alloys on their
magnetic properties, martensitic transformation characteristics, transformation hysteresis, and
magnetocaloric properties was studied using wavelength-dispersive X-ray spectroscopy, differen-
tial scanning calorimetry, and the temperature and field dependence of the magnetization.
Ni45Co5Mn40Sn10 alloy has a very low transformation hysteresis; however, the martensitic transfor-
mation temperatures are notably above room temperature, which is not desirable for magnetic re-
frigeration applications. In this study, small quantities of Nb substitution were shown to drastically
shift the transformation temperatures to lower temperatures, at a rate of 68 K/at. % Nb, which is
needed for household refrigeration. The austenite Curie temperature also decreased with increasing
Nb content. However, a decrease in the latent heat of the martensitic transition was observed, which
negatively affects the magnetic field-induced adiabatic temperature change capability. Still, the rel-
atively large transformation entropy and the low transformation hysteresis make the Nb-doped
Ni45Co5Mn40Sn10 alloys potential candidates for solid state refrigeration near room temperature.VC 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4903494]
Magnetic shape memory alloys (MSMAs) have attracted
considerable interest as a new type of functional materials
due to their promising features for actuation and sensing.
Since the discovery of large magnetic field induced strain
(MFIS) in Ni2MnGa,1 extensive research has been conducted
on the magnetic field-induced martensitic transition
(MT).2–14 These alloys undergo a first-order magnetic transi-
tion from a high symmetry phase (austenite) to a low symme-
try phase (martensite) upon cooling. This transition is
associated with sharp changes in magnetization.15 Due to the
strong coupling between the crystallographic structure and
magnetism, these Ni-Mn based MSMAs show other attractive
properties such as magnetocaloric effect (MCE) and magne-
toresistance (MR).6–11
The MCE is defined as a temperature change that
occurs when a magnetic field is applied to a material. This
principle can be used in solid state refrigeration schemes.
Magnetocaloric materials (MCM) are classified as conven-
tional MCM and inverse MCM. Conventional MCM heats
up with the application of magnetic field and cools down
when magnetic field is removed. The most well-known con-
ventional MCM are Gd5Si2Ge2,16 LaFe13�xSixH,17,18 and
MnFeP (As,Ge).19,20 Among the inverse MCM, the most
well-known materials are Heusler type Ni-Mn-(In, Sn, Sb)-
based MSMAs.2,21–24 Due to the strong magneto-structural
coupling, a magnetic field can induce a simultaneous
change of magnetic and lattice entropies; therefore, one can
observe the so called “giant MCE” (GMCE) in these mate-
rials. Studies up to now have revealed that the maximum
MCE is obtained when the structural and magnetic transi-
tion temperatures overlap.15 It is reported8 that there are at
least three important characteristics while evaluating a
magnetocaloric material: (1) the effect must occur near
room temperature for room temperature applications, (2)
the MCE and refrigeration capacity (RC) must be signifi-
cant at reasonable applied magnetic field levels, and (3) the
process must be reversible with respect to changing/revers-
ing magnetic field and show low hysteresis loss. In addition
to improving the achievable MCE in NiMn-(In,Sn,Sb)
alloys, it is a well-known fact that low transformation hys-
teresis also promotes cyclic reversibility.25,26 Therefore, it
is important to explore the behavior of MSMAs that exhibit
low hysteresis.
Ni45Co5Mn40Sn10 was reported to exhibit low thermal
hysteresis while also exhibiting one of the highest magnet-
ization changes across the martensitic transformation (DM)
among the Ni-Co-Mn-Sn alloy family.25 However, this par-
ticular alloy has a major drawback for MCE applications,
that is, the large magnetization change, and MT occurs well
above room temperature, i.e., �400 K.25 From the practical
point of view, the material should exhibit the structural tran-
sition around room temperature.
Many investigations have been conducted on the effect
of 3d transition-metal doping on the structural phase
transitions, magnetic, and magnetocaloric characteristics
of Ni-Mn-Sn based MSMAs.27–33 However, the effect of
4d-transition-metal substitution has not yet been widely
a)Author to whom correspondence should be addressed. Electronic mail:
0003-6951/2014/105(23)/231910/5/$30.00 VC 2014 AIP Publishing LLC105, 231910-1
APPLIED PHYSICS LETTERS 105, 231910 (2014)
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
165.91.74.118 On: Wed, 02 Sep 2015 21:34:00
studied with the exception of the work in Ref. 34. In the
present work, we report that the doping of 4d-transition
metal substitutions (Nb in this case) is an effective way for
moving attractive high temperature properties (i.e., low hys-
teresis and high magnetization difference (DM) between the
austenite and martensite phases upon martensitic transforma-
tion) closer to room temperature.
Polycrystalline Ni45�xNbxCo5Mn40Sn10 (x¼ 1 and 1.5)
alloys were arc-melted on a water-cooled copper hearth from
high-purity elements with the appropriate amounts of Ni,
Nb, Mn, Co, and Sn under argon protection, after purging
the chamber several times under vacuum. After fabrication,
these alloys were then sealed in quartz tubes under Ar and
annealed at 1173 K for 24 h followed by water quenching.
Polycrystalline samples were cut from the ingots using a
low-speed diamond saw and used as samples for differential
scanning calorimetry (DSC) and magnetization measure-
ments. The compositions of the alloys were determined using
wavelength-dispersive X-ray spectroscopy (WDS) at 3 loca-
tions within 4 different grains after homogenization. The
compositions (in at. %) of the samples were determined as
Ni43.660.2Mn39.460.16Co560.1Sn10.860.1Nb1.060.02 (denoted as
Nb1) and Ni43.460.1Mn39.360.3Co560.05Sn10.760.2Nb1.660.03
(denoted as Nb1.5). Microstructure observations performed
to identify the room temperature phases of the alloys are pre-
sented in Fig. 1. Both alloys show a mixture of the martens-
ite and austenite at room temperature (Figs. 1(a) and 1(b)).
The DSC curves for Nb1 and Nb1.5 alloys are shown in
the lower insets of Figs. 2(a) and 2(d), respectively. Both for-
ward and reverse martensitic transitions are accompanied by
well-defined peaks, arising from the latent heat of the
transformation. The characteristic temperatures for the mar-
tensitic transition are determined to be Ms¼ 351 K,
Mf¼ 335 K, As¼ 347 K, and Af¼ 361 K for the Nb1 sample,
and Ms¼ 304 K, Mf¼ 290 K, As¼ 305 K, and Af¼ 318 K for
the Nb1.5 sample. Here, Ms is the martensite start, Mf is the
martensite finish, As is the austenite start, and Af is the aus-
tenite finish temperatures. The Curie temperature of the aus-
tenite, TAC, is also observed in the DSC curve for the Nb1.5
sample (Fig. 2(f)). However, the intense peaks of the forward
and reverse transformation mask the TAC of the Nb1 sample.
The thermal hysteresis defined as (Af�Ms) and reported as
6 K for Ni45Co5Mn40Sn10 (parent alloy).25 We observed ther-
mal hysteresis as 10 K for Nb1 and 14 K for Nb1.5 from the
DSC results. Still, the thermal hysteresis of the Nb1 and
Nb1.5 samples is one of the lowest among the other studied
compositions of the NiCoMnSn system.25 In addition, the
TAC was not observed in DSC curves in the parent alloy, but
from M(T) data it was observed to be around 445 K.25 The
addition of Nb causes a decrease in the martensitic transfor-
mation temperatures with the rate of about 68 K/at. %Nb.
The temperature dependence of magnetization at several
magnetic fields for Nb1 and Nb1.5 is shown in Figs. 2(a) and
2(b) and Figs. 2(d) and 2(e), respectively. The characteristic
temperatures for the martensitic transition from DSC meas-
urements indicated as arrows in Figs. 2(b) and 2(d). In all
M(T) measurements, the field heated (FH) data do not retrace
the field cooled (FC) data but show a hysteresis, which is the
fingerprint of a first-order structural transition, as found in
the DSC results. As in the parent alloy, the samples show
multiple transitions upon cooling: (i) from the paramagnetic
(PM) austenite phase to a ferromagnetic (FM) austenite
FIG. 1. Backscattered electron (BSE)
images of the microstructure for
Ni45�xNbxMn40Co5Sn10 (a) x¼ 1 and
(b) x¼ 1.5, showing a mixture of
the austenite and martensite phases.
The images were taken at room
temperature.
FIG. 2. Magnetization (M(T)) curves
of Ni45�xNbxMn40Co5Sn10 alloys
under the magnetic fields of 1 T, 3 T,
5 T, and 7 T for x¼ 1 (a) and x¼ 1.5
(d). The upper insets show M(T) at
50 mT for x¼ 1 (b) and x¼ 1.5 (e).
The lower insets show DSC curves of
Nb1 (c) and Nb1.5 (f).
231910-2 Emre et al. Appl. Phys. Lett. 105, 231910 (2014)
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
165.91.74.118 On: Wed, 02 Sep 2015 21:34:00
phase at TAC; and (ii) from the FM austenite phase to the low
magnetic state (PM or antiferromagnetic (AF)35) martensite
at the martensitic transition temperature. For both alloys, the
martensite has a low magnetization, leading to a large DMacross the martensitic transition. The magnetization
increases abruptly at TAC� 355 K and 345 K during cooling
for the Nb1 and Nb1.5 samples, respectively. Due to the for-
ward and reverse martensitic transformation, magnetization
shows abrupt decrease/increase at 340 K/345 K for the Nb1
sample and at 300 K/306 K for the Nb1.5 sample. The width
of the hysteresis of the Nb1 and Nb1.5 samples from M(T)
measurements is found to be around 5 K and 6 K in 50 mT,
respectively. This is almost constant under higher magnetic
fields.
Figure 3(a) shows the transformation entropy (DS) and
the As temperature change as a function of Nb composition.
As has a linear dependency to the Nb content, whereas the
transformation entropy shows a non-linear trend. In Fig. 3(b),
the martensitic transformation temperatures under several
magnetic fields are also plotted. With increasing magnetic
field, the martensitic transitions shift toward lower tempera-
tures, in agreement with the magnetic field stabilization of fer-
romagnetic austenite phase. The characteristic temperatures,
Mf and As, linearly decrease with the field at a rate of
dMf /dH¼�2.5 K T�1 and dAs/dH¼�2.0 K T�1 for the
Nb1.5 sample and dMf/dH¼�1.1 K T�1 and dAs/dH
¼�0.9 K T�1 for the Nb1 sample, which are close to those
reported in Ref. 25 (�2.6 K/T). The transformation ranges
(Ms�Mf and Af�As) are less than 7 K for the Nb1 sample
and less than 22 K for the Nb1.5 sample. These transition
ranges are an indication of the difficulty of phase front motion
between the martensite and austenite. Large transition ranges
indicate large stored elastic energy within the crystal lattice,
and highly compatible austenite and martensite phases exhibit
sharp transitions. The shift in the transition temperature with
magnetic field is accounted for by the Claussius-Clapeyron
equation: DT � DMDS
� �DH, where DM and DS are the differ-
ences in the magnetization and entropy between the austenite
and martensite phases, respectively. DSs of the Nb1 and
Nb1.5 samples are calculated from the enthalpy data obtained
by DSC as DS¼ 41.4 J/kg K and 34 J/kg K, respectively.
Using the equation above with DH¼ 7 T and DM for the Nb1
and Nb1.5 samples as 60 emu/g and 70 emu/g, respectively,
DTs are calculated as 10.1 K and as 14.4 K, respectively.
Figures 4(a) and 4(c) show M(H) curves of Nb1 and
Nb1.5, respectively, at several temperatures. The measure-
ment is done by following the procedure reported in Ref. 36.
The M(H) curves of Fig. 4(a) at 325–341 K exhibit typical
magnetic behavior of austenite, and the curves at
344 K–353 K temperature interval clearly indicate magnetic
field-induced phase transformation for the Nb1 sample. In
this sample, the maximum magnetic hysteresis of �2.4 T is
observed at 347 K. In the case of the Nb1.5 sample, the M(H)
(Fig. 4(c)) curves exhibit metamagnetic transition almost for
all temperatures, but it is more clear for the temperature inter-
val of 287 K–312 K. However, the magnetic hysteresis is not
as clear as that for the Nb1 sample. The M(H) results are in
line with M(T) curves shown in Figs. 2(a) and 2(d).
We have estimated the field induced entropy change
(DS) around the martensitic transformation for both samples
using the relationship DSðTK; 0! HÞ ¼ 1DTk½ÐH
0MTkþ1
dH �ÐH0
MTkdH� numerically from the M(H) isotherms. The tem-
perature dependence of the DS is plotted in Figs. 4(b) and
4(d), for Nb1 and Nb1.5, respectively. For both samples, the
sign of DS is positive in the range of MT. However, DS is
negative for temperatures close to TAC since @M
@T < 0 for this
case. The inverse nature of the magnetocaloric effect is con-
sistent with the magnetic field stabilization of the cubic
phase. The maxima DS in a magnetic field of 5 T are about
48 J K�1 kg�1 for Nb1 and 10 J K�1 kg�1for Nb1.5 around
MT. Such a large MCE is comparable to those of
Ni44Mn43Cu2Sn11, Ni43Mn43Co4Sn11, and Ni50Mn34Co2Sn14,
which exhibit DS of approximately 50 J kg�1 K�1 for a field
change of 0–5 T, thus makes Nb1 a good candidate for MCE.
The values of DS around TAC are smaller since the magnetic
transition is second-order and magnetization changes over a
broader temperature range than the first-order martensitic trans-
formation. The measured values of DS for the Nb1 sample are
larger than those for Nb1.5 since the Nb1 sample shows almost
complete reversible martensitic transformation under 5 T field
loading, while the Nb1.5 sample only partially transforms
reversibly at all temperatures when employing the discontinu-
ous heating protocol.21 The width of the DS vs. T peaks for the
Nb1 sample also increases with increasing magnetic field
thereby leading to an increase in the refrigerant capacity.21
In conclusion, the magnetic and martensitic transforma-
tion behavior of Ni45�xNbxCo5Mn40Sn10 (x¼ 1 and 1.5)
alloys were investigated. It was found that the addition of
small amount of Nb leads to a sharp decrease in martensitic
transformation and TAC temperatures. Namely, the
FIG. 3. (a) Changes in the transformation entropy of the forward martensitic
transformation and As temperature as a function of Nb composition. (b) The
martensitic transformation temperatures determined from the M(T) curves
(open symbols for the Nb1.5 sample and closed symbols for the Nb1 sam-
ple). Lines correspond to linear regression to the data.
231910-3 Emre et al. Appl. Phys. Lett. 105, 231910 (2014)
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
165.91.74.118 On: Wed, 02 Sep 2015 21:34:00
transformation temperatures decrease approximately with a
rate of 68 K/at. %Nb. Furthermore, the martensite finish
temperature Mf linearly decreases with the field at a rate
dMf /dH¼�1.1 K T�1 and �2.5 K T�1 for the Nb1 and
Nb1.5 samples, respectively. Application of magnetic field
induces a decrease in martensitic transformation temperatures
and the magnetic field-induced phase transformation from
martensite to austenite was confirmed. The detrimental effect
on the transformation hysteresis and the reversibility of the
magnetocaloric effect were relatively minor due to very low
hysteresis. The large magnetization and low hysteresis make
the Nb1 sample a potential candidate for magnetic shape
memory, energy conversion, and solid-state refrigeration.
This work was supported by the U.S. National Science
Foundation, Division of Materials Research, Metals and
Metallic Nanostructures Program, Grant No. 1108396, under
the umbrella of the Materials World Network Initiative.
Additional support was received from the U.S. National
Science Foundation under Grant No. DMR 08-44082, which
supports the International Materials Institute for Multi-
functional Materials for Energy Conversion (IIMEC) at
Texas A&M University.
1K. Ullakko, J. K. Huang, C. Kantner, R. C. O’Handley, and V. V.
Kokorin, Appl. Phys. Lett. 69, 1966 (1996).2R. Kainuma, Y. Imano, W. Ito, Y. Sutou, H. Morito, S. Okamoto, O.
Kitakami, K. Oikawa, A. Fujita, T. Kanomata, and K. Ishida, Nature
(London) 439, 957 (2006).3D. Y. Cong, S. Roth, M. P€otschke, C. H€urrich, and L. Schultz, Appl. Phys.
Lett. 97, 021908 (2010).4H. E. Karaca, I. Karaman, B. Basaran, Y. I. Chumlyakov, and H. J. Maier,
Adv. Funct. Mater. 19(7), 983 (2009).5R. Y. Umetsu, A. Sheikh, W. Ito, B. Ouladdiaf, K. R. A. Ziebeck, T.
Kanomata, and R. Kainuma, Appl. Phys. Lett. 98, 042507 (2011).6V. K. Sharma, M. K. Chattopadhyay, K. H. B. Shaeb, A. Chouhan, and S.
B. Roy, Appl. Phys. Lett. 89, 222509 (2006).7S. Y. Yu, L. Ma, G. D. Liu, Z. H. Liu, J. L. Chen, Z. X. Cao, G. H. Wu, B.
Zhang, and X. X. Zhang, Appl. Phys. Lett. 90, 242501 (2007).8A. K. Pathak, I. Dubenko, C. Pueblo, S. Stadler, and N. Ali, J. Appl. Phys.
107, 09A907 (2010).
9J. A. Monroe, I. Karaman, B. Basaran, W. Ito, R. Y. Umetsu, R. Kainuma,
K. Koyama, and Y. I. Chumlyakov, Acta Mater. 60(20), 6883 (2012).10A. K. Pathak, M. Khan, I. Dubenko, S. Stadler, and N. Ali, Appl. Phys.
Lett. 90, 262504 (2007).11H. C. Xuan, D. H. Wang, C. L. Zhang, Z. D. Han, B. X. Gu, and Y. W.
Du, Appl. Phys. Lett. 92, 102503 (2008).12I. Karaman, H. E. Karaca, B. Basaran, D. C. Lagoudas, Y. I. Chumlyakov,
and H. J. Maier, Scr. Mater. 55, 403 (2006).13H. E. Karaca, I. Karaman, B. Basaran, D. C. Lagoudas, Y. I. Chumlyakov,
and H. J. Maier, Acta Mater. 55, 4253 (2007).14H. E. Karaca, I. Karaman, A. L. Brewer, B. Basaran, Y. I. Chumlyakov,
and H. J. Maier, Scr. Mater. 58, 815 (2008).15T. Krenke, E. Duman, M. Acet, E. F. Wassermann, X. Moya, L. Ma~nosa,
and A. Planes, Nat. Mater. 4, 450 (2005).16V. K. Pecharsky and K. A. Gschneidner, Jr., Phys. Rev. Lett. 78,
4494–4497 (1997).17A. Fujita, S. Fujieda, Y. Hasegawa, and K. Fukamichi, Phys. Rev. B 67,
104416 (2003).18J. Lyubina, K. Nenkov, L. Schultz, and O. Gutfleisch, Phys. Rev. Lett.
101, 177203 (2008).19O. Tegus, E. Br€uck, K. H. J. Buschow, and F. R. de Boer, Nature
(London) 415, 150 (2002).20A. Yan, K. H. M€uller, L. Schultz, and O. Gutfleisch, J. Appl. Phys. 99,
08K903 (2006).21N. M. Bruno, C. Yegin, I. Karaman, J. H. Che, J. H. Ross, J. Liu, and J. Li,
Acta Mater. 74, 66 (2014).22M. Chmielus, X. X. Zhang, C. Witherspoon, D. C. Dunand, and P.
M€ullner, Nat. Mater. 8, 863 (2009).23L. Ma~nosa, D. Gonz�alez-Alonso, A. Planes, E. Bonnot, M. Barrio, J. L.
Tamarit, S. Aksoy, and M. Acet, Nat. Mater. 9, 478 (2010).24J. Liu, T. G. Woodcock, N. Scheerbaum, and O. Gutfleisch, Acta Mater.
57, 4911 (2009).25V. Srivastava, X. Chen, and R. D. James, Appl. Phys. Lett. 97, 014101
(2010).26B. Emre, S. Yuce, E. Stern-Taulats, A. Planes, S. Fabbrici, F. Albertini,
and L. Manosa, J. Appl. Phys. 113, 213905 (2013).27T. Krenke, E. Duman, M. Acet, X. Moya, L. Ma~nosa, and A. Planes,
J. Appl. Phys. 102(3), 033903 (2007).28R. Sahoo, A. K. Nayak, K. G. Suresh, and A. K. Nigam, J. Appl. Phys.
109(12), 123904 (2011).29Z. Wu, Z. Liu, H. Yang, Y. Liu, and G. Wu, Intermetallics 19(12),
1839–1848 (2011).30W. Ito, X. Xu, R. Y. Umetsu, T. Kanomata, K. Ishida, and R. Kainuma,
Appl. Phys. Lett. 97(24), 242512 (2010).31Y. Feng, J. H. Sui, Z. Y. Gao, J. Zhang, and W. Cai, Mater. Sci. Eng., A
507(1–2), 174–178 (2009).32M. Kataoka, K. Endo, N. Kudo, T. Kanomata, H. Nishihara, T. Shishido,
R. Y. Umetsu, M. Nagasako, and R. Kainuma, Phys. Rev. B 82(21),
214423 (2010).
FIG. 4. M(H) curves for Nb1 (a) and
Nb1.5 (c). Magnetic field induced en-
tropy change (magnetocaloric effect)
as a function of temperature for
selected values of the magnetic field
(1, 2, 3, 4, 5, 6, and 7 T) of Nb1 (b)
and Nb1.5 (d).
231910-4 Emre et al. Appl. Phys. Lett. 105, 231910 (2014)
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
165.91.74.118 On: Wed, 02 Sep 2015 21:34:00
33D. E. Soto-Parra, F. Alvarado-Hernandez, O. Ayala, R. A. Ochoa-Gamboa,
H. Flores-Z�u~niga, and D. Rios-Jara, J. Alloys Compd. 464(1–2), 288 (2008).34Z. Han, X. Chen, Y. Zhang, J. Chen, B. Qian, X. Jiang, D. Wang, and Y.
Du, J. Alloys Compd. 515, 114 (2012).
35S. Aksoy, M. Acet, P. P. Deen, L. Ma~nosa, and A. Planes, Phys. Rev. B
79, 212401 (2009).36J. Liu, N. Scheerbaum, J. Lyubina, and O. Gutfleisch, Appl. Phys. Lett. 93,
102512 (2008).
231910-5 Emre et al. Appl. Phys. Lett. 105, 231910 (2014)
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
165.91.74.118 On: Wed, 02 Sep 2015 21:34:00