Using the pulsed laser ablation technique, Fe73.5Cu1Nb3Si15.5B7 amorphous thin films, with smooth and uniform surfaces, have been deposited on glass and silicon substrates. Based on the information provided by the thermomagnetic analysis, the nanocrystalline state was achieved after the thermal treatment per-formed at 460 C. In nanocrystalline state, the samples present an 80 %  lower coercive magnetic field and a 3.5 times higher saturation magnetization with respect to the as-deposited state.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3515

Chiriac, H.

Dobromir, M.

Neagu, M.

Velicu, I.L.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 1, 01NTF09(3pp) (2013)   2304-1862/2013/2(1) 01NTF09(3) 01NTF09-1  2013 Sumy State University FeCuNbSiB Thin Films Deposited by Pulsed Laser Deposition: Structural and Magnetic Properties  M. Dobromir1, I.L. Velicu1, M. Neagu1, H. Chiriac2  1 Faculty of Physics, Alexandru Ioan Cuza University, Blvd. Carol I, No. 11, RO-700506, Iasi, Romania 2 National Institute of Research & Development for Technical Physics, Blvd. Mangeron, No. 47, RO-700050, Iasi, Romania  (Received 19 May 2013; published online 30 August 2013)  Using the pulsed laser ablation technique, Fe73.5Cu1Nb3Si15.5B7 amorphous thin films, with smooth and uniform surfaces, have been deposited on glass and silicon substrates. Based on the information provided by the thermomagnetic analysis, the nanocrystalline state was achieved after the thermal treatment per-formed at 460 C. In nanocrystalline state, the samples present an 80  lower coercive magnetic field and a 3.5 times higher saturation magnetization with respect to the as-deposited state.  Keywords: Amorphous and Nanocrystalline Magnetic Materials, Magnetic Properties, Thin films, Magne-to-Optical Kerr Effect.   PACS number(s): 42.65.Hw, 62.23.Pq, 75.60.Ej   1. INTRODUCTION  FeCuNbSiB amorphous and nanocrystalline thin films are attractive in a wide range of engineering appli-cations. The nanocrystalline state can be induced by ad-equate thermal treatment applied to the amorphous pre-cursors. In the last years, due to the large number of industrial applications with stringent requirements and to the increasing development of technology, there has been a strong diversification, improvement and expan-sion of the techniques used for obtaining amorphous soft magnetic thin films [1-7]. The microstructure optimiza-tion of FeCuNbSiB soft magnetic thin films is of great importance with the view of enhancing their magnetic properties for micromagnetic device applications. Simi-larly with the case of amorphous ribbons and wires with the same compositional formula, in the nanocrystalline state an important improvement of the soft magnetic properties can be obtained [1-4, 6-9].  The aim of this paper is to investigate the structural, topological, and magnetic properties of Fe73.5Cu1Nb3Si15.5B7 thin films obtained by pulsed laser ablation. The samples have been investigated in as-deposited state and after thermal treatments.  2. EXPERIMENTAL DETAILS  FeCuNbSiB thin films have been prepared by pulsed laser deposition technique, using as target ribbons with the nominal composition Fe73.5Cu1Nb3Si15.5B7 (Vacuum-schmelze GmbH). The films were deposited on glass and silicon substrates. The depositions were carried out under high vacuum (10-6 Torr), by means of a XeCl excimer laser (308 nm wavelength) with the pulse duration, repetition rate and pulse energy of 30 ns, 25 Hz and 55 mJ, respec-tively. By varying the deposition time, films with thick-ness between 150 nm and 300 nm have been prepared. Techniques such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and interferometry were used to characterize the composition, the structural properties, the morphology and the thickness of the obtained films. The XPS anal-yses were carried out with a PHI 5000 VersaProbe (Φ ULVAC-PHI, INC.) spectrometer (Al Kα radiation, 1486.7 eV). The XRD measurements were performed using a Bruker AXS D8 Advance diffractometer with CuKα radiation (1.5418 Å), in Bragg-Brentano geometry. The AFM analyses were carried out using a NT-MDT Solver Pro-M AFM, in tapping mode. A magnetization dependence on temperature was analyzed in the tem-peratures range 23C – 850 C. The volume magnetic behavior of the samples was investigated by a differen-tial inductive method at 50 Hz, using an integrating fluxmeter. The surface magnetic behavior was investi-gated by means of magneto-optical Kerr effect, in longi-tudinal configuration. The samples have been investigated in as-deposited state and after furnace annealing at temperatures be-tween 400C and 480C, for 60 minutes, in high vacuum (10-6 Torr).  3. RESULTS AND DISCUSSION  X-ray diffraction studies confirmed the amorphicity of all as-deposited samples.  The AFM topographical scans have revealed uniform surfaces, with a root-mean-square roughness value of about 1.5 nm.  The X-ray photoelectron spectroscopy investigations demonstrated that the stoichiometry of the target has been achieved in the deposited films. Fig. 1 presents a wide-scan XPS spectrum recorded for a FeCuNbSiB thin film in as-deposited state, in the binding energies range from 0 to 1200 eV. The sputter cleaning of the surface was done under ultra high vacuum conditions on a 3  3 mm2 area by using an Ar+ ion beam (500 V, 500 nA, 1 minute). All the binding energies at various peaks were calibrated by the binding energy of C 1s (284.5 eV). From the pre-sented spectrum, it can be clearly seen the presence of Fe, Cu, Nb, Si, B elements near the surface of the analyzed film. Surface contamination elements like carbon and oxygen can also be observed. The presence of oxygen in the XPS spectrum reflects the surface oxidation process due to the film exposure into the atmosphere.  M. DOBROMIR, I.L. VELICU, M. NEAGU, H. CHIRIAC PROC. NAP 2, 01NTF09 (2013)   01NTF09-2   Fig. 1 – Wide-scan XPS spectrum for an as-deposited amorphous FeCuNbSiB thin film.  In order to get information on the crystallization ki-netics, magnetization dependences on temperature were registered for samples deposited on silicon substrate. Fig. 2 presents a normalized thermomagnetic curve, registered for a Fe73.5Cu1Nb3Si15.5B7 thin film. The criti-cal temperatures (i.e. Curie temperature of the amor-phous phase, TCam, first crystallization temperature, Tx, and Curie temperature of the crystalline phase, TCcr) were determined from the thermomagnetic curve using the intersecting tangents method [10] and also, for a better accuracy, using the differential method, d2M/dT2 [11]. The determination of Curie temperature of the amorphous phase by the differential method of Tauxe is also presented in Fig. 2. As it can be seen, the magneti-zation rapidly decreases with the temperature incre-ment up to TCam  363 C, reaching beyond this (when the film is in paramagnetic state) a value close to zero. The beginning of the crystallization process (precipita-tion of the crystalline phase with higher Curie temper-ature) at about 457 oC leads to an abrupt increase in the magnetization value. The Curie temperature of the crystalline phase is about 620 oC. According to this in-formation, the nanocrystalline state of the Fe73.5Cu1Nb3Si15.5B7 thin films can be achieved through thermal treatments performed at temperatures around 460 C.    Fig. 2 – Normalized thermomagnetic curve for an as-deposited Fe73.5Cu1Nb3Si15.5B7  thin film (silicon substrate).  The crystallization processes indicated by the ther-momagnetic analysis are also confirmed by the XRD results. According to these, for samples thermally treat-ed in the temperature range of the first crystallization temperature, the nanocrystalline state has been achieved. The softest magnetic properties have been obtained after the thermal treatment performed at 460 C. After this treatment, the film structure consists of ultra-fine bcc -Fe(Si) grains, with average size of about 15 nm, uniformly dispersed in a residual Fe-Nb-B amorphous matrix. The average -Fe(Si) grain size of the nanocrys-talline phase was estimated using the Scherrer formula [4]. Fig. 3 presents bulk hysteresis loops for a Fe73.5Cu1Nb3Si15.5B7 thin film (200 nm thickness) in as-deposited state and after the thermal treatment per-formed for 1 hour, at 460 C.  For samples thermally treated in the mentioned conditions, the bulk coercive magnetic field value decreases with about 80 , while the saturation magnetization becomes 3.5 times higher with respect to the as-deposited state.     Fig. 3 – Bulk hysteresis loops for a Fe73.5Cu1Nb3Si15.5B7 film in as-deposited state and after thermal treatment at 460 oC.  The bulk coercive magnetic field for the as-deposited thin films decreases with about 43 , when the film thickness increases from 150 nm to 300 nm.  Magneto-optical Kerr analyses have revealed an al-most identical surface magnetic behavior, the only dif- FECUNBSIB THIN FILMS DEPOSITED BY PULSED LASER… PROC. NAP 2, 01NTF09 (2013)   01NTF09-3 ference being that the surface coercive magnetic field value is about 5  higher than the bulk coercive magnet-ic field value. This difference may be due to the existing surface imperfections.  4. CONCLUSION  The pulsed laser deposition technique allows obtain-ing Fe73.5Cu1Nb3Si15.5B7 amorphous thin films with smooth and uniform surfaces. In order to establish the optimum annealing tem-peratures which lead to achieving the nanocrystalline state, the crystallization kinetics was investigated for the obtained films. An important improvement of soft magnetic proper-ties has been obtained after the thermal treatment per-formed at 460 C. Future studies will aim to establish new deposition parameters in order to improve the soft magnetic prop-erties for FINEMET-type thin films obtained using pulsed laser ablation technique.  AKNOWLEDGEMENTS  This work was supported by the European Social Fund in Romania, under the responsibility of the Man-aging Authority for the Sectoral Operational Pro-gramme for Human Resources Development 2007-2013 under Grant POSDRU/CPP 107/DMI 1.5/S/78342.    REFERENCES  1. D. Szewieczek, T. Raszka, Journal of Achievements in Materials and Manufacturing Engineering 18, 179 (2006). 2. F. Celegato, M. Coisson, P. Tiberto, F. Vinai, M. Baricco, Phys. Status Solidi C: Current Topics in Solid State Phys-ics 8, 10.1002/pssc.201000197 (2011). 3. J. Moulin, F. Mazaleyrat, A. Mendez, E. Dufour-Gergama, J. Magn. Magn. Mater. 322, 1275 (2010). 4. X.D. Li, W.Z. Yuan, Z.J. Zhao, X.Z. Wang, J.Z. Ruan, X.L. Yang, J. Magn. Magn. Mater. 279, 429 (2004). 5. S. Acquaviva, A.P. Caricato, E. D’Anna, M. Fernandez, A. Luches, Z. Frait, E. Majkova, M. Ozvold, S. Luby, P. Mengucci, Thin Solid Films 433, 252 (2003). 6. P. Sharma, A. Gupta, J. Magn. Magn. Mater. 288, 347 (2005). 7. I.-L. Velicu, M. Neagu, H. Chiriac, V. Tiron, M. Dobromir, IEEE T. Magn. 48, 1336 (2012). 8. G. Herzer, Nanocrystalline Soft Magnetic Alloys (in Hand-book of Magnetic Materials, edited by K.H.J. Buschow (Ed.), Elsevier Science BV, Amsterdam-Lausanne: 1997). 9. M.H. Phan, H.X. Peng, M.R. Wisnom, S.C. Yu, N. Chau, Compos. Part A – Appl. S. 37, 191 (2006). 10. C.S. Grommé, T.L. Wright, D.L. Peck, J. Geophys. Res. 74, 5277 (1969). 11. L. Tauxe, Paleomagnetic Principles and Practice, 1st ed. (Springer: New York: 1998).  

FeCuNbSiB Thin Films Deposited by Pulsed Laser Deposition: Structural and Magnetic Properties

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 1, 01NTF09(3pp) (2013) 
 
 
2304-1862/2013/2(1) 01NTF09(3) 01NTF09-1  2013 Sumy State University 
FeCuNbSiB Thin Films Deposited by Pulsed Laser Deposition: Structural and Magnetic 
Properties 
 
M. Dobromir1, I.L. Velicu1, M. Neagu1, H. Chiriac2 
 
1 Faculty of Physics, Alexandru Ioan Cuza University, Blvd. Carol I, No. 11, RO-700506, Iasi, Romania 
2 National Institute of Research & Development for Technical Physics, Blvd. Mangeron, No. 47, RO-700050, Iasi, 
Romania 
 
(Received 19 May 2013; published online 30 August 2013) 
 
Using the pulsed laser ablation technique, Fe73.5Cu1Nb3Si15.5B7 amorphous thin films, with smooth and 
uniform surfaces, have been deposited on glass and silicon substrates. Based on the information provided 
by the thermomagnetic analysis, the nanocrystalline state was achieved after the thermal treatment per-
formed at 460 C. In nanocrystalline state, the samples present an 80  lower coercive magnetic field and 
a 3.5 times higher saturation magnetization with respect to the as-deposited state. 
 
Keywords: Amorphous and Nanocrystalline Magnetic Materials, Magnetic Properties, Thin films, Magne-
to-Optical Kerr Effect. 
 
 PACS number(s): 42.65.Hw, 62.23.Pq, 75.60.Ej 
 
 
1. INTRODUCTION 
 
FeCuNbSiB amorphous and nanocrystalline thin 
films are attractive in a wide range of engineering appli-
cations. The nanocrystalline state can be induced by ad-
equate thermal treatment applied to the amorphous pre-
cursors. In the last years, due to the large number of 
industrial applications with stringent requirements and 
to the increasing development of technology, there has 
been a strong diversification, improvement and expan-
sion of the techniques used for obtaining amorphous soft 
magnetic thin films [1-7]. The microstructure optimiza-
tion of FeCuNbSiB soft magnetic thin films is of great 
importance with the view of enhancing their magnetic 
properties for micromagnetic device applications. Simi-
larly with the case of amorphous ribbons and wires with 
the same compositional formula, in the nanocrystalline 
state an important improvement of the soft magnetic 
properties can be obtained [1-4, 6-9].  
The aim of this paper is to investigate the structural, 
topological, and magnetic properties of 
Fe73.5Cu1Nb3Si15.5B7 thin films obtained by pulsed laser 
ablation. The samples have been investigated in as-
deposited state and after thermal treatments. 
 
2. EXPERIMENTAL DETAILS 
 
FeCuNbSiB thin films have been prepared by pulsed 
laser deposition technique, using as target ribbons with 
the nominal composition Fe73.5Cu1Nb3Si15.5B7 (Vacuum-
schmelze GmbH). The films were deposited on glass and 
silicon substrates. The depositions were carried out under 
high vacuum (10-6 Torr), by means of a XeCl excimer laser 
(308 nm wavelength) with the pulse duration, repetition 
rate and pulse energy of 30 ns, 25 Hz and 55 mJ, respec-
tively. By varying the deposition time, films with thick-
ness between 150 nm and 300 nm have been prepared. 
Techniques such as X-ray photoelectron spectroscopy 
(XPS), X-ray diffraction (XRD), atomic force microscopy 
(AFM) and interferometry were used to characterize the 
composition, the structural properties, the morphology 
and the thickness of the obtained films. The XPS anal-
yses were carried out with a PHI 5000 VersaProbe (Φ 
ULVAC-PHI, INC.) spectrometer (Al Kα radiation, 
1486.7 eV). The XRD measurements were performed 
using a Bruker AXS D8 Advance diffractometer with 
CuKα radiation (1.5418 Å), in Bragg-Brentano geometry. 
The AFM analyses were carried out using a NT-MDT 
Solver Pro-M AFM, in tapping mode. A magnetization 
dependence on temperature was analyzed in the tem-
peratures range 23C – 850 C. The volume magnetic 
behavior of the samples was investigated by a differen-
tial inductive method at 50 Hz, using an integrating 
fluxmeter. The surface magnetic behavior was investi-
gated by means of magneto-optical Kerr effect, in longi-
tudinal configuration. 
The samples have been investigated in as-deposited 
state and after furnace annealing at temperatures be-
tween 400C and 480C, for 60 minutes, in high vacuum 
(10-6 Torr). 
 
3. RESULTS AND DISCUSSION 
 
X-ray diffraction studies confirmed the amorphicity of 
all as-deposited samples.  
The AFM topographical scans have revealed uniform 
surfaces, with a root-mean-square roughness value of 
about 1.5 nm.  
The X-ray photoelectron spectroscopy investigations 
demonstrated that the stoichiometry of the target has 
been achieved in the deposited films. Fig. 1 presents a 
wide-scan XPS spectrum recorded for a FeCuNbSiB thin 
film in as-deposited state, in the binding energies range 
from 0 to 1200 eV. The sputter cleaning of the surface was 
done under ultra high vacuum conditions on a 3  3 mm2 
area by using an Ar+ ion beam (500 V, 500 nA, 1 minute). 
All the binding energies at various peaks were calibrated 
by the binding energy of C 1s (284.5 eV). From the pre-
sented spectrum, it can be clearly seen the presence of Fe, 
Cu, Nb, Si, B elements near the surface of the analyzed 
film. Surface contamination elements like carbon and 
oxygen can also be observed. The presence of oxygen in 
the XPS spectrum reflects the surface oxidation process 
due to the film exposure into the atmosphere. 
 M. DOBROMIR, I.L. VELICU, M. NEAGU, H. CHIRIAC PROC. NAP 2, 01NTF09 (2013) 
 
 
01NTF09-2 
 
 
Fig. 1 – Wide-scan XPS spectrum for an as-deposited amorphous FeCuNbSiB thin film. 
 
In order to get information on the crystallization ki-
netics, magnetization dependences on temperature were 
registered for samples deposited on silicon substrate. 
Fig. 2 presents a normalized thermomagnetic curve, 
registered for a Fe73.5Cu1Nb3Si15.5B7 thin film. The criti-
cal temperatures (i.e. Curie temperature of the amor-
phous phase, TCam, first crystallization temperature, Tx, 
and Curie temperature of the crystalline phase, TCcr) 
were determined from the thermomagnetic curve using 
the intersecting tangents method [10] and also, for a 
better accuracy, using the differential method, d2M/dT2 
[11]. The determination of Curie temperature of the 
amorphous phase by the differential method of Tauxe is 
also presented in Fig. 2. As it can be seen, the magneti-
zation rapidly decreases with the temperature incre-
ment up to TCam  363 C, reaching beyond this (when 
the film is in paramagnetic state) a value close to zero. 
The beginning of the crystallization process (precipita-
tion of the crystalline phase with higher Curie temper-
ature) at about 457 oC leads to an abrupt increase in 
the magnetization value. The Curie temperature of the 
crystalline phase is about 620 oC. According to this in-
formation, the nanocrystalline state of the 
Fe73.5Cu1Nb3Si15.5B7 thin films can be achieved through 
thermal treatments performed at temperatures around 
460 C. 
 
 
 
Fig. 2 – Normalized thermomagnetic curve for an as-deposited 
Fe73.5Cu1Nb3Si15.5B7  thin film (silicon substrate). 
 
The crystallization processes indicated by the ther-
momagnetic analysis are also confirmed by the XRD 
results. According to these, for samples thermally treat-
ed in the temperature range of the first crystallization 
temperature, the nanocrystalline state has been 
achieved. 
The softest magnetic properties have been obtained 
after the thermal treatment performed at 460 C. After 
this treatment, the film structure consists of ultra-fine 
bcc -Fe(Si) grains, with average size of about 15 nm, 
uniformly dispersed in a residual Fe-Nb-B amorphous 
matrix. The average -Fe(Si) grain size of the nanocrys-
talline phase was estimated using the Scherrer formula 
[4]. Fig. 3 presents bulk hysteresis loops for a 
Fe73.5Cu1Nb3Si15.5B7 thin film (200 nm thickness) in as-
deposited state and after the thermal treatment per-
formed for 1 hour, at 460 C.  For samples thermally 
treated in the mentioned conditions, the bulk coercive 
magnetic field value decreases with about 80 , while 
the saturation magnetization becomes 3.5 times higher 
with respect to the as-deposited state.  
 
 
 
Fig. 3 – Bulk hysteresis loops for a Fe73.5Cu1Nb3Si15.5B7 film in 
as-deposited state and after thermal treatment at 460 oC. 
 
The bulk coercive magnetic field for the as-deposited 
thin films decreases with about 43 , when the film 
thickness increases from 150 nm to 300 nm.  
Magneto-optical Kerr analyses have revealed an al-
most identical surface magnetic behavior, the only dif-
 FECUNBSIB THIN FILMS DEPOSITED BY PULSED LASER… PROC. NAP 2, 01NTF09 (2013) 
 
 
01NTF09-3 
ference being that the surface coercive magnetic field 
value is about 5  higher than the bulk coercive magnet-
ic field value. This difference may be due to the existing 
surface imperfections. 
 
4. CONCLUSION 
 
The pulsed laser deposition technique allows obtain-
ing Fe73.5Cu1Nb3Si15.5B7 amorphous thin films with 
smooth and uniform surfaces. 
In order to establish the optimum annealing tem-
peratures which lead to achieving the nanocrystalline 
state, the crystallization kinetics was investigated for 
the obtained films. 
An important improvement of soft magnetic proper-
ties has been obtained after the thermal treatment per-
formed at 460 C. 
Future studies will aim to establish new deposition 
parameters in order to improve the soft magnetic prop-
erties for FINEMET-type thin films obtained using 
pulsed laser ablation technique. 
 
AKNOWLEDGEMENTS 
 
This work was supported by the European Social 
Fund in Romania, under the responsibility of the Man-
aging Authority for the Sectoral Operational Pro-
gramme for Human Resources Development 2007-2013 
under Grant POSDRU/CPP 107/DMI 1.5/S/78342.  
 
 
REFERENCES 
 
1. D. Szewieczek, T. Raszka, Journal of Achievements in 
Materials and Manufacturing Engineering 18, 179 (2006). 
2. F. Celegato, M. Coisson, P. Tiberto, F. Vinai, M. Baricco, 
Phys. Status Solidi C: Current Topics in Solid State Phys-
ics 8, 10.1002/pssc.201000197 (2011). 
3. J. Moulin, F. Mazaleyrat, A. Mendez, E. Dufour-Gergama, 
J. Magn. Magn. Mater. 322, 1275 (2010). 
4. X.D. Li, W.Z. Yuan, Z.J. Zhao, X.Z. Wang, J.Z. Ruan, 
X.L. Yang, J. Magn. Magn. Mater. 279, 429 (2004). 
5. S. Acquaviva, A.P. Caricato, E. D’Anna, M. Fernandez, 
A. Luches, Z. Frait, E. Majkova, M. Ozvold, S. Luby, 
P. Mengucci, Thin Solid Films 433, 252 (2003). 
6. P. Sharma, A. Gupta, J. Magn. Magn. Mater. 288, 347 
(2005). 
7. I.-L. Velicu, M. Neagu, H. Chiriac, V. Tiron, M. Dobromir, 
IEEE T. Magn. 48, 1336 (2012). 
8. G. Herzer, Nanocrystalline Soft Magnetic Alloys (in Hand-
book of Magnetic Materials, edited by K.H.J. Buschow 
(Ed.), Elsevier Science BV, Amsterdam-Lausanne: 1997). 
9. M.H. Phan, H.X. Peng, M.R. Wisnom, S.C. Yu, N. Chau, 
Compos. Part A – Appl. S. 37, 191 (2006). 
10. C.S. Grommé, T.L. Wright, D.L. Peck, J. Geophys. Res. 74, 
5277 (1969). 
11. L. Tauxe, Paleomagnetic Principles and Practice, 1st ed. 
(Springer: New York: 1998). 
 


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FeCuNbSiB Thin Films Deposited by Pulsed Laser Deposition: Structural and Magnetic Properties

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