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Transformation of surface domain structure in Co-rich amorphous wires
Sensors and Actuators B 126 (2007) 235–239
Transformation of surface domain structure in Co-rich amorphous wires A. Chizhik a,∗ , J. Gonzalez a , A. Zhukov a , J.M. Blanco b a
Departamento F´ısica de Materiales, Facultad de Qu´ımica, UPV/EHU, P.O. Box 1072, 20018 San Sebasti´an, Spain b Departamento F´ısica Aplicada I, EUPDS, UPV/EHU, Plaza Europa, 1, 20018 San Sebasti´ an, Spain Available online 11 January 2007
Abstract The process of magnetization reversal in Co-rich nearly zero magnetostrictive amorphous wire having circumferential magnetic anisotropy in the outer shell has been studied. The investigations have been performed using magneto-optical Kerr effect microscope. The main regularities of the domain structure transformation have been elucidated. The nucleation and the movement of the domain wall and magnetic vortexes are the basic components of the magnetization reversal determined the value of the giant magneto-impedance effect in these wires. © 2006 Elsevier B.V. All rights reserved. Keywords: Amorphous wire; Magneto-optical Kerr effect; Giant magneto-impedance; Domain wall
1. Introduction
2. Experimental details
Co-rich amorphous wires with nearly zero magnetostriction attract special attention, because they exhibit a giant magneto-impedance (GMI) effect [1,2] that has recently been found in these wires. This GMI effect is of great interest in sensor applications [3]. The importance of investigating the magnetic structures in the surface area of the wires is demonstrated by the known correlation between the GMI and the magnetic skin effect. The present work is devoted to the investigation of magnetic domain structure of an amorphous wire because of its special place in the origin of the GMI effect. The electrical impedance in these nearly zero magnetostrictve amorphous wires is very sensitive to a surface magnetic configuration, therefore, the characteristic features of impedance behavior are closely related to a quasi-static magnetization process. During the experiments, special attention was paid to the behavior of the magnetic domain structure under the action of an axial magnetic field, considering that the GMI effect is very sensitive to the axial magnetic field. The investigations have been performed using the magneto-optic Kerr effect technique, which appears as a very useful method for the study of the domain structure in amorphous ferromagnetic wires [4].
The investigations have been performed in a nearly zero magnetostrictive, amorphous wire having circumferential magnetic anisotropy in the outer shell. The Co-rich ferromagnetic wires of nominal composition (Co94 Fe6 )72.5 Si12.5 B15 (diameter 120 m) obtained by the in-rotating-water quenching technique were produced by Unitika Ltd. The length of the studied wires was 7 cm. The process of magnetization reversal in the surface area of the wires has been studied by a Kerr microscope employing an image processor. The images of the magnetic domains were of black, white or grey colour depending on the direction of the magnetization. A pair of Helmholtz coils provided an axial magnetic field. The wedge plane has been prepared in the surface of the studied wire.
∗
Corresponding author. Tel.: +34 943 018611; fax: +34 943 017130. E-mail address: [email protected] (A. Chizhik).
0925-4005/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2006.12.014
3. Results and discussion The transformation of the domain structure has been studied in four different places in the surface of the wire (schematically are shown in Fig. 1): three places in the wedge-shaped plane surface and one place in the cylindrical surface of the wire. The results of the domain structure transformation in the place closest to the end of the wedge (position 1 in Fig. 1) are presented in Fig. 2. The black and white colours demonstrate that the direction of the magnetization is perpendicular to the wire axis. The domains with the magnetization oriented along the
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Fig. 1. Schematic diagram of the studied wires.
Fig. 2. Images of surface domain structure for the position 1 in the wedge. (a) −10, (b) −2, (c) −0.3, (d) 0.03, (e) 0.3, (f) 1.3, (g) 2, (h) 10 Oe.
wire axis have a grey colour. Fig. 2 shows the magnetization reversal process from −10 Oe (Fig. 2a) up to +10 Oe (Fig. 2h). Two processes take place at the first stage of the magnetization reversal (Fig. 2b): rotation of the magnetization reversal from the axial direction to the circular direction (the colour of the domain changes) and the nucleation of circular domains (black–white domain structure appears). At the second stage (Fig. 2b–d) the domain walls motion between circular domains is observed. At some step (Fig. 2e) the mono-domain circular structure occupies the wire surface. Further, once more we can see the circular domain nucleation (Fig. 2f) and domain walls motion (Fig. 2g). At the final stage, the rotation of the magnetization to the axial direction happens and we once more observe the mono-domain of grey colour. Fig. 3 reflects the domain structure transformation in the place 2 (Fig. 1). As for the above-mentioned case, the rotation of the magnetization at the first and at the final steps of the magnetization reversal takes place. It realises in the change of the colour of the domain structure from grey to black–white and vice versa. In this series of photos we present the magnetization reversal from +10 up to −10 Oe, therefore, the white domain nucleation is observed at the first step in contrast to the previous case. The main difference of the present magnetization reversal process from the case 1 is the following: the domain with circular magnetization is formed inside the wedge (Fig. 3b) and develops towards the border of it. The regular domain structure with the circular domains is not observed. At the last step the irregular domain structure (Fig. 3g) loses the black–white contrast that means the rotation of the magnetization towards the axial direction. The transformation of the domain structure for the wide wedge (place 3) in Fig. 1, is shown in Fig. 4. There are some special features which could characterise this process. First, in some pictures the coexistence of domains with three different contrast is observed. The magnetization reversal occurs as a rearrangement of the domain structure but not by the regular domain walls motion. As before, at the first step, the simultaneous rotation of the magnetization and the formation of the domain structure take place. The transformation by the rearrangement happens between Fig. 4c–e. During the transition from Fig. 4d to e, a considerable part of the black (white) domains changes the colour to white (black) by jump without the domain walls motion. The black and white domains go to the border of the wedge and form their relatively regular structure of the circular domains (Fig. 4d and e). Fig. 5 presents the pictures of the surface domain structure transformation for the cylindrical part of the wire which was not polished. Keeping some of the above-mentioned regularities, this process has a very special features. As before, the rotation of the magnetization takes place at the initial and final stages. Also the formation of the domains with the circular direction of the magnetization accompanies the magnetization reversal, but the formation and the motion of these domains are specific enough. At some stage the complex multi-domain structure appears (Fig. 5c). The domains with four different directions of the magnetization exist on this stage. The transformation of this domain structure is accompanied by the domain walls motion
A. Chizhik et al. / Sensors and Actuators B 126 (2007) 235–239
237
Fig. 4. Images of surface domain structure for the position 3 in the wedge. (a) −10, (b) −2, (c) −0.8, (d) −0.4, (e) 0.14, (f) 2, (g) 10 Oe.
Fig. 3. Images of surface domain structure for the position 2 in the wedge. (a) 10, (b) 5, (c) 2, (d) 0.03, (e) −0.03, (f) −1, (g) −2, (h) −10 Oe.
and the jump-like rearrangement of whole domain structure (Fig. 5c–e). The four-domain structure can be considered as a specific magnetic vortex [5]. Rotation of the magnetization by 360◦ appears in this vortex. Under an axial magnetic field the vortex moves compactly in the surface of the wire taking part in this way in the magnetization reversal. It is possible to see the point where the black domain wall is changed by the white one. This point could be considered as a centre of the vortex. The four presented series of the magnetization reversal could be considered within (certain) limits as complement date. At the same time, this complement could not be considered as a com-
plete one. As is known, the treatment of the surface of the wire could cause some change of the distribution of the stresses in the wire, that could produce the change of the magnetic structure. Nevertheless, the magnetic structure of the wire is determined mainly by the in-rotating-water quenching preparation process and we consider that the obtained results supplement each other greatly. The domain structure transformation in the axial magnetic field has the common regularity in the surface of the wire and deeper. At the initial and final steps, the rotation of the magnetization takes place towards the circular and the axial directions, consequently. The formation of the domain structure also in the general feature. For the surface areas of the these domain contain the magnetization directed to the circular direction or inclined weakly from it. Closer to the central part of the wire, the domains with very different direction of the magnetization, including the
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A. Chizhik et al. / Sensors and Actuators B 126 (2007) 235–239
The interrelationship of the surface and volume domain structure also cold be noted. 4. Conclusion The magnetization reversal in the Co-rich amorphous wire having high value of the GMI effect has been studied. The investigations have been performed in the experimental configuration similar to the GMI effect: an external magnetic field has been applied along the wire axis. The Kerr microscopy images have been obtained from different places of the plane wedge prepared in the surface of the wire and in the cylindrical surface of the untreated wire. The main regularity of the domain structure transformation has been elucidated. At the first and final stages, the rotation of the magnetization takes place towards the circular and the axial directions, respectively. The nucleation of domains and the formation of the multi-domain structure are the basic elements of the magnetization reversal process in the presence of the axial magnetic field. The high sensitivity of the circular domain structure to the axial magnetic field confirms the strong correlation between inner and surface domain structure in the studied wire. The transformation of the multi-domain structure occurs by the domain walls displacement and by the jumping rearrangement. The nucleation and the motion of the 180◦ domain walls and 360◦ magnetic vortexes result to be the key features of the studied process of the magnetization reversal, which has a strong influence on the value of the GMI effect. References [1] R.S. Beach, A.E. Berkowitz, Giant magnetic field dependent impedance of amorphous FeCoSiB wire, Appl. Phys. Lett. 64 (1994) 3652. [2] L.V. Panina, K. Mohri, Magneto-impedance effect in amorphous wires, Appl. Phys. Lett. 65 (1994) 1189. [3] K. Mohri, T. Uchiyama, L.P. Shen, C.M. Cai, L.V. Panina, Sensitive micro magnetic sensor family utilizing magneto-impedance (MI) and stressimpedance (SI) effects for intelligent measurements and controls, Sens. Actuators A: Phys. 91 (2001) 85. [4] A. Chizhik, J. Gonzalez, A. Zhukov, J.M. Blanco, Magnetization reversal of Co-rich wires in circular magnetic field, J. Appl. Phys. 91 (2002) 537. [5] A. Hubert, R. Schafer, Magnetic Domains, Springer, Berlin, 1998, p. 315.
Biographies
Fig. 5. Images of surface domain structure for the position 4. (a) −10, (b) −0.1, (c) 0.14, (d) 0.17, (e) 0.2, (f) 0.3 Oe.
axial direction, could coexist. One special process, which was observed practically in all of the studied cases, is the replacement of the domain with perpendicular magnetization by the domain with the revised direction of the magnetization. This replacement is the key moment in the place of the domain transformation in the GMI effect. The sharp reversal of the magnetization to 180◦ (related to the domain wall motion) or to 360◦ (related to the vortex motion) causes the great jump of the circumferential permeability, which determines mainly the value of the GMI effect.
Dr. A. Chizhik graduated in 1982 from the Kharkov State University (Ukraine). In 1991 received PhD degree from the Institute for Low Temperature Physics and Engineering of the Academy of Science of Ukraine. He is presently working as contracted researcher (Ramon y Cajal programme) at the Department of the Materials Physics of the University of Basque Country in San Sebastian (Spain). His current fields of interest are magneto-optical investigations of amorphous and nanocrystalline magnetic materials. He has published about 70 referred papers in the international science journals. Prof. J. Gonzalez graduated in 1977 from the Navarra University. In 1987 received PhD degree from the University of Basque Country. He is presently working as professor of the University of Basque Country in San Sebastian. His current fields of interest are novel magnetic materials, amorphous and nanocrystalline ferromagnetic materials. He has published more than 200 referred papers in the international journals on studies of magnetic materials, edited a conference proceedings, gave a number of invited talks on few international conferences on Magnetism, wrote a chapter in the book “Advanced Magnetic Materials”, article for the “Enciclopedia of NanoScience and Nanotechnology” etc.
A. Chizhik et al. / Sensors and Actuators B 126 (2007) 235–239 Dr. A. P. Zhukov graduated in 1980 from the Physics-Chemistry Department of the Moscow Steel and Alloys Institute. In 1988 received PhD degree from the Institute of Solid State Physics of the Russian Acad. Sci. He is presently working as contracted researcher (Ramon y Cajal programme) at the Department of the Materials Physics of the University of Basque Country in San Sebastian. His current fields of interest are novel magnetic materials, amorphous ferromagnetic materials, in particular micro-wires, giant magneto-impedance, giant magnetoresistance, magnetoelastic sensors and nanocrystalline materials. He has published about 200 referred papers in the international journals on studies of magnetic materials, edited a conference proceedings, gave a number of invited talks on few international conferences on Magnetism, wrote a chapter
239
in the book “Advanced Magnetic Materials”, article for the “Enciclopedia of NanoScience and Nanotechnology” etc. Dr. J. M. Blanco graduated in 1987 from the University of Basque Country. In 1992 received Ph.D. degree from the University of Basque Country. He is presently working as associate professor of the University of Basque Country in San Sebastian. His current fields of interest are novel magnetic materials, amorphous and nanocrystalline ferromagnetic materials. He has published more than 150 referred papers in the international journals on studies of magnetic materials.
Transformation of surface domain structure in Co-rich amorphous wires A. Chizhik a,∗ , J. Gonzalez a , A. Zhukov a , J.M. Blanco b a
Departamento F´ısica de Materiales, Facultad de Qu´ımica, UPV/EHU, P.O. Box 1072, 20018 San Sebasti´an, Spain b Departamento F´ısica Aplicada I, EUPDS, UPV/EHU, Plaza Europa, 1, 20018 San Sebasti´ an, Spain Available online 11 January 2007
Abstract The process of magnetization reversal in Co-rich nearly zero magnetostrictive amorphous wire having circumferential magnetic anisotropy in the outer shell has been studied. The investigations have been performed using magneto-optical Kerr effect microscope. The main regularities of the domain structure transformation have been elucidated. The nucleation and the movement of the domain wall and magnetic vortexes are the basic components of the magnetization reversal determined the value of the giant magneto-impedance effect in these wires. © 2006 Elsevier B.V. All rights reserved. Keywords: Amorphous wire; Magneto-optical Kerr effect; Giant magneto-impedance; Domain wall
1. Introduction
2. Experimental details
Co-rich amorphous wires with nearly zero magnetostriction attract special attention, because they exhibit a giant magneto-impedance (GMI) effect [1,2] that has recently been found in these wires. This GMI effect is of great interest in sensor applications [3]. The importance of investigating the magnetic structures in the surface area of the wires is demonstrated by the known correlation between the GMI and the magnetic skin effect. The present work is devoted to the investigation of magnetic domain structure of an amorphous wire because of its special place in the origin of the GMI effect. The electrical impedance in these nearly zero magnetostrictve amorphous wires is very sensitive to a surface magnetic configuration, therefore, the characteristic features of impedance behavior are closely related to a quasi-static magnetization process. During the experiments, special attention was paid to the behavior of the magnetic domain structure under the action of an axial magnetic field, considering that the GMI effect is very sensitive to the axial magnetic field. The investigations have been performed using the magneto-optic Kerr effect technique, which appears as a very useful method for the study of the domain structure in amorphous ferromagnetic wires [4].
The investigations have been performed in a nearly zero magnetostrictive, amorphous wire having circumferential magnetic anisotropy in the outer shell. The Co-rich ferromagnetic wires of nominal composition (Co94 Fe6 )72.5 Si12.5 B15 (diameter 120 m) obtained by the in-rotating-water quenching technique were produced by Unitika Ltd. The length of the studied wires was 7 cm. The process of magnetization reversal in the surface area of the wires has been studied by a Kerr microscope employing an image processor. The images of the magnetic domains were of black, white or grey colour depending on the direction of the magnetization. A pair of Helmholtz coils provided an axial magnetic field. The wedge plane has been prepared in the surface of the studied wire.
∗
Corresponding author. Tel.: +34 943 018611; fax: +34 943 017130. E-mail address: [email protected] (A. Chizhik).
0925-4005/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2006.12.014
3. Results and discussion The transformation of the domain structure has been studied in four different places in the surface of the wire (schematically are shown in Fig. 1): three places in the wedge-shaped plane surface and one place in the cylindrical surface of the wire. The results of the domain structure transformation in the place closest to the end of the wedge (position 1 in Fig. 1) are presented in Fig. 2. The black and white colours demonstrate that the direction of the magnetization is perpendicular to the wire axis. The domains with the magnetization oriented along the
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A. Chizhik et al. / Sensors and Actuators B 126 (2007) 235–239
Fig. 1. Schematic diagram of the studied wires.
Fig. 2. Images of surface domain structure for the position 1 in the wedge. (a) −10, (b) −2, (c) −0.3, (d) 0.03, (e) 0.3, (f) 1.3, (g) 2, (h) 10 Oe.
wire axis have a grey colour. Fig. 2 shows the magnetization reversal process from −10 Oe (Fig. 2a) up to +10 Oe (Fig. 2h). Two processes take place at the first stage of the magnetization reversal (Fig. 2b): rotation of the magnetization reversal from the axial direction to the circular direction (the colour of the domain changes) and the nucleation of circular domains (black–white domain structure appears). At the second stage (Fig. 2b–d) the domain walls motion between circular domains is observed. At some step (Fig. 2e) the mono-domain circular structure occupies the wire surface. Further, once more we can see the circular domain nucleation (Fig. 2f) and domain walls motion (Fig. 2g). At the final stage, the rotation of the magnetization to the axial direction happens and we once more observe the mono-domain of grey colour. Fig. 3 reflects the domain structure transformation in the place 2 (Fig. 1). As for the above-mentioned case, the rotation of the magnetization at the first and at the final steps of the magnetization reversal takes place. It realises in the change of the colour of the domain structure from grey to black–white and vice versa. In this series of photos we present the magnetization reversal from +10 up to −10 Oe, therefore, the white domain nucleation is observed at the first step in contrast to the previous case. The main difference of the present magnetization reversal process from the case 1 is the following: the domain with circular magnetization is formed inside the wedge (Fig. 3b) and develops towards the border of it. The regular domain structure with the circular domains is not observed. At the last step the irregular domain structure (Fig. 3g) loses the black–white contrast that means the rotation of the magnetization towards the axial direction. The transformation of the domain structure for the wide wedge (place 3) in Fig. 1, is shown in Fig. 4. There are some special features which could characterise this process. First, in some pictures the coexistence of domains with three different contrast is observed. The magnetization reversal occurs as a rearrangement of the domain structure but not by the regular domain walls motion. As before, at the first step, the simultaneous rotation of the magnetization and the formation of the domain structure take place. The transformation by the rearrangement happens between Fig. 4c–e. During the transition from Fig. 4d to e, a considerable part of the black (white) domains changes the colour to white (black) by jump without the domain walls motion. The black and white domains go to the border of the wedge and form their relatively regular structure of the circular domains (Fig. 4d and e). Fig. 5 presents the pictures of the surface domain structure transformation for the cylindrical part of the wire which was not polished. Keeping some of the above-mentioned regularities, this process has a very special features. As before, the rotation of the magnetization takes place at the initial and final stages. Also the formation of the domains with the circular direction of the magnetization accompanies the magnetization reversal, but the formation and the motion of these domains are specific enough. At some stage the complex multi-domain structure appears (Fig. 5c). The domains with four different directions of the magnetization exist on this stage. The transformation of this domain structure is accompanied by the domain walls motion
A. Chizhik et al. / Sensors and Actuators B 126 (2007) 235–239
237
Fig. 4. Images of surface domain structure for the position 3 in the wedge. (a) −10, (b) −2, (c) −0.8, (d) −0.4, (e) 0.14, (f) 2, (g) 10 Oe.
Fig. 3. Images of surface domain structure for the position 2 in the wedge. (a) 10, (b) 5, (c) 2, (d) 0.03, (e) −0.03, (f) −1, (g) −2, (h) −10 Oe.
and the jump-like rearrangement of whole domain structure (Fig. 5c–e). The four-domain structure can be considered as a specific magnetic vortex [5]. Rotation of the magnetization by 360◦ appears in this vortex. Under an axial magnetic field the vortex moves compactly in the surface of the wire taking part in this way in the magnetization reversal. It is possible to see the point where the black domain wall is changed by the white one. This point could be considered as a centre of the vortex. The four presented series of the magnetization reversal could be considered within (certain) limits as complement date. At the same time, this complement could not be considered as a com-
plete one. As is known, the treatment of the surface of the wire could cause some change of the distribution of the stresses in the wire, that could produce the change of the magnetic structure. Nevertheless, the magnetic structure of the wire is determined mainly by the in-rotating-water quenching preparation process and we consider that the obtained results supplement each other greatly. The domain structure transformation in the axial magnetic field has the common regularity in the surface of the wire and deeper. At the initial and final steps, the rotation of the magnetization takes place towards the circular and the axial directions, consequently. The formation of the domain structure also in the general feature. For the surface areas of the these domain contain the magnetization directed to the circular direction or inclined weakly from it. Closer to the central part of the wire, the domains with very different direction of the magnetization, including the
238
A. Chizhik et al. / Sensors and Actuators B 126 (2007) 235–239
The interrelationship of the surface and volume domain structure also cold be noted. 4. Conclusion The magnetization reversal in the Co-rich amorphous wire having high value of the GMI effect has been studied. The investigations have been performed in the experimental configuration similar to the GMI effect: an external magnetic field has been applied along the wire axis. The Kerr microscopy images have been obtained from different places of the plane wedge prepared in the surface of the wire and in the cylindrical surface of the untreated wire. The main regularity of the domain structure transformation has been elucidated. At the first and final stages, the rotation of the magnetization takes place towards the circular and the axial directions, respectively. The nucleation of domains and the formation of the multi-domain structure are the basic elements of the magnetization reversal process in the presence of the axial magnetic field. The high sensitivity of the circular domain structure to the axial magnetic field confirms the strong correlation between inner and surface domain structure in the studied wire. The transformation of the multi-domain structure occurs by the domain walls displacement and by the jumping rearrangement. The nucleation and the motion of the 180◦ domain walls and 360◦ magnetic vortexes result to be the key features of the studied process of the magnetization reversal, which has a strong influence on the value of the GMI effect. References [1] R.S. Beach, A.E. Berkowitz, Giant magnetic field dependent impedance of amorphous FeCoSiB wire, Appl. Phys. Lett. 64 (1994) 3652. [2] L.V. Panina, K. Mohri, Magneto-impedance effect in amorphous wires, Appl. Phys. Lett. 65 (1994) 1189. [3] K. Mohri, T. Uchiyama, L.P. Shen, C.M. Cai, L.V. Panina, Sensitive micro magnetic sensor family utilizing magneto-impedance (MI) and stressimpedance (SI) effects for intelligent measurements and controls, Sens. Actuators A: Phys. 91 (2001) 85. [4] A. Chizhik, J. Gonzalez, A. Zhukov, J.M. Blanco, Magnetization reversal of Co-rich wires in circular magnetic field, J. Appl. Phys. 91 (2002) 537. [5] A. Hubert, R. Schafer, Magnetic Domains, Springer, Berlin, 1998, p. 315.
Biographies
Fig. 5. Images of surface domain structure for the position 4. (a) −10, (b) −0.1, (c) 0.14, (d) 0.17, (e) 0.2, (f) 0.3 Oe.
axial direction, could coexist. One special process, which was observed practically in all of the studied cases, is the replacement of the domain with perpendicular magnetization by the domain with the revised direction of the magnetization. This replacement is the key moment in the place of the domain transformation in the GMI effect. The sharp reversal of the magnetization to 180◦ (related to the domain wall motion) or to 360◦ (related to the vortex motion) causes the great jump of the circumferential permeability, which determines mainly the value of the GMI effect.
Dr. A. Chizhik graduated in 1982 from the Kharkov State University (Ukraine). In 1991 received PhD degree from the Institute for Low Temperature Physics and Engineering of the Academy of Science of Ukraine. He is presently working as contracted researcher (Ramon y Cajal programme) at the Department of the Materials Physics of the University of Basque Country in San Sebastian (Spain). His current fields of interest are magneto-optical investigations of amorphous and nanocrystalline magnetic materials. He has published about 70 referred papers in the international science journals. Prof. J. Gonzalez graduated in 1977 from the Navarra University. In 1987 received PhD degree from the University of Basque Country. He is presently working as professor of the University of Basque Country in San Sebastian. His current fields of interest are novel magnetic materials, amorphous and nanocrystalline ferromagnetic materials. He has published more than 200 referred papers in the international journals on studies of magnetic materials, edited a conference proceedings, gave a number of invited talks on few international conferences on Magnetism, wrote a chapter in the book “Advanced Magnetic Materials”, article for the “Enciclopedia of NanoScience and Nanotechnology” etc.
A. Chizhik et al. / Sensors and Actuators B 126 (2007) 235–239 Dr. A. P. Zhukov graduated in 1980 from the Physics-Chemistry Department of the Moscow Steel and Alloys Institute. In 1988 received PhD degree from the Institute of Solid State Physics of the Russian Acad. Sci. He is presently working as contracted researcher (Ramon y Cajal programme) at the Department of the Materials Physics of the University of Basque Country in San Sebastian. His current fields of interest are novel magnetic materials, amorphous ferromagnetic materials, in particular micro-wires, giant magneto-impedance, giant magnetoresistance, magnetoelastic sensors and nanocrystalline materials. He has published about 200 referred papers in the international journals on studies of magnetic materials, edited a conference proceedings, gave a number of invited talks on few international conferences on Magnetism, wrote a chapter
239
in the book “Advanced Magnetic Materials”, article for the “Enciclopedia of NanoScience and Nanotechnology” etc. Dr. J. M. Blanco graduated in 1987 from the University of Basque Country. In 1992 received Ph.D. degree from the University of Basque Country. He is presently working as associate professor of the University of Basque Country in San Sebastian. His current fields of interest are novel magnetic materials, amorphous and nanocrystalline ferromagnetic materials. He has published more than 150 referred papers in the international journals on studies of magnetic materials.