- Email: [email protected]
Magnetoelastic sensor of liquid level based on magnetoelastic properties of Co-rich microwires
Sensors and Actuators 81 Ž2000. 129–133 www.elsevier.nlrlocatersna
Magnetoelastic sensor of liquid level based on magnetoelastic properties of Co-rich microwires A. Zhukov a
b,),1
, A.F. Cobeno ˜ a, J. Gonzalez b, J.M. Blanco a, P. Aragoneses a, L. Dominguez a
Departamento Fisica Aplicada I y Departamento de Electronica y Telecomunicaciones ´ ´ EUITI, UniÕersidad Paıs ´ Vasco, AÕda Felipe IV 1B, 20011, San Sebastian, Spain b Departamento Fisica de Materiales, Facultad de Quımica, UniÕersidad Paıs ´ ´ Vasco, 1072, 20080, San Sebastian, Spain
Abstract The effect of external tensile stress on the hysteresis loops of nearly-zero magnetostrictive glass-coated amorphous microwires of ŽCo 100yx Mn x . 0.75 Si 10 B15 Ž10 - x - 11. and Co 56.5 Fe 6.5 Ni 10 B l6 Si 11 compositions of metallic nucleus has been studied. All hysteresis loops have a rectangular shape without applied stress. Significant changes in the shape of the hysteresis loop are produced by the application of tensile stress, particularly the hysteresis loop of the sample ŽCo 92 Mn 8 . 75 Si 10 B15 under a loading of 10 g, becoming flat with reduced values of both remanence and coercivity. These changes of the hysteresis loop with the external strain have been used to design a magnetoelastic sensor of liquid level. q 2000 Elsevier Science S.A. All rights reserved. Keywords: Rectangular hysteresis loop; Switching field; Magnetoelastic energy
1. Introduction The well-known Žsince the 1960s. Taylor–Ulitovski method w1x has been recently employed for the preparation of tiny Žaround 20 mm in diameter. glass-coated amorphous microwires exhibiting magnetic bistability ŽMB. effect w2–4x. Recently, it has been found that these microwires exhibit MB even for very short samples and for nearly zero-magnetostrictive alloys w5x. On the other hand, microwires of compositions with negative magnetostriction do not exhibit MB, as a difference with respect to ‘commercial’ amorphous wires showing MB w5x. The observed peculiarities in the compositional dependence of MB, as well as the enhanced values of remanence were explained in terms of the additional stresses arising from the outer glass w5–8x. Depending on the thickness of glass coating, the switching field is at least one order of magnitude larger than that of melt-spun wires w2–4,7x. A nonhysteretic character of the magnetisation curves for negative magnetostriction compositions ŽCo 68.5Y2.5 Si 14.5 B 14.5 . was found
) 1
Corresponding author. On leave from the ‘AmoTec’, Kishinev, Moldova.
and explained in Refs. w5,9x taking into account the stresses arising from the glass coating. It was experimentally confirmed in Ref. w9x by the appearance of MB after glass removal in the alloy with initially nonhysteretic hysteresis loop. Only a few measurements of the effect of external tensile stresses on parameters of the hysteresis loops in a single Fe-rich composition were performed in Refs. w4,10x. No systematic study of Co-rich microwires with MB has been reported until now. In the case of the conventional Fe 75 B12.5 Si 15 amorphous wire with a diameter of 125 mm, the switching field H U is very sensitive to heat treatments and especially to applied stress w6,7,11,13x. It was found that the experimental dependence of H U on applied tensile stress s roughly follows a s 1r2 law for Fe-rich wires. Co-rich wires did not show such dependence. Consequently, a nucleation mechanism was invoked to explain the stress dependence of the switching field in Fe-rich wires and a propagation of domain walls—in Co-rich w12,13x. On the other hand, the effect of external stresses on the switching field is of special interest for the technical applications of these microwires. The aim of this work is to present and to analyse new data concerning the magnetic properties of Co-rich microwires, to study the effect
0924-4247r00r$ - see front matter q 2000 Elsevier Science S.A. All rights reserved. PII: S 0 9 2 4 - 4 2 4 7 Ž 9 9 . 0 0 1 5 2 - 1
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
130
Table 1 Compositions and labels of investigated samples Alloy
Label
Metallic nucleus radius rm Žmm.
Glass-coating thickness t Žmm.
Ratio r s trrm q t
ŽCo 89 Mn 11 . 0.75 Si 10 B15 ŽCo 89.5 Mn 10.5 . 0.75 Si 10 B15 ŽCo 90 Mn 10 . 0.75 Si 10 B15 Co 56.5 Fe 6.5 Ni 10 B l6 Si 11
A B C D
5.4 3.625 5 5
6 5.87 5.6 6.75
0.53 0.35 0.431 0.425
of external tensile stresses on their magnetic properties and also to assess them for technical applications.
2. Experimental Amorphous microwires of nominal compositions ŽCo 100y x Mn x . 75 Si 10 B 15 Ž x s 8, 9 and 10 . and Co 56.5 Fe 6.5 Ni 10 B l6 Si 11 of similar geometric dimensions Ždiameter of metallic nucleus and thickness of glass coating. were obtained by the Taylor–Ulitovski technique w1,2,6x Žsee details in Table 1.. This method essentially consists in drawing a Pyrex-like glass tube containing the molten metal into a wire. Introduction of the receiving bobbin w6x allows to obtain samples of a few kilometers in length. Pieces 12 cm in length have been used for magnetic measurements. The axial Mz –Hz hysteresis loop of the samples was obtained by means of a conventional induction method at 50 Hz with a possibility to measure the hysteresis loops under load, P, attached to the sample. It allows the
determination of the switching field, H U , and the ratio remanence to saturation magnetisation, m r . The magnetic field, Hz , was applied by a Helmholtz coil system with a maximum field of 5 kArm. More details on the experimental set-up can be found in Ref. w10x. Four different samples labelled A, B, C and D respectively have been investigated Žsee details in Table 1..
3. Experimental results and their discussion Fig. 1a–d show the axial hysteresis loops of all studied samples. All the samples exhibited a single and large Barkhausen jump. From Fig. 1A–C it can be noted that the switching field, H U , increases with x from 15 Arm at x s 10 up to 50 Arm at x s 11. The experimental dependencies of the switching field, H U , and remanence, m r , on external tensile strain are presented in Fig. 2. It is clear, that the curves H U Ž P . and m r Ž P . for samples A–C are quite different. H U is roughly stress-independent for small P and then starts to increase
Fig. 1. Axial hysteresis loops for both studied compositions of the microwires: ŽA., ŽB., ŽC. and ŽD., respectively.
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
in sample A. On the contrary, sample B first shows a slight increasing and then a decreasing of H U with P. Samples A and B always showed rectangular hysteresis loop. The sample C has a rectangular hysteresis at zero applied stress, although its switching field is rather small. With the increase in weight, P, H U and m r decreased and finally MB disappeared. The behaviour of sample D results to be quite similar to that of sample C, when H U decreases with P, but its hysteresis loop is still rectangular. These changes of hysteresis loops Žits shape, coercivity and remanence. under the effect of the external tensile stress can be explained from a stress dependence of the
131
magnetostriction constant. It is well known that in similar Co-rich compositions of amorphous alloys containing Fe, the magnetostriction constant changes in sign from positive to negative with increasing Co content w14,15x. It was found experimentally w12,13x that
l Ž s . s l Ž 0 . y Bs
Ž 1.
where lŽ0. is the saturation magnetostriction constant at zero applied stresses and B is a positive coefficient of the order of 10y1 0 MPa. The main difference between conventional wires and microwires is that the latter contain a glass coating. The
Fig. 2. Effect of the external stress on the critical field H U and the reduced remanence m r of samples A–D. The scales in the insets of Žb. and Žc. are the same for each figure.
132
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
Fig. 2 Žcontinued..
thermal expansion coefficients of metallic nucleus and glass coating are rather different. This difference introduces strong internal stresses one to two orders of magnitude larger than in the case of conventional wires. The existence of high quenched-in internal stresses seems to be able to change significantly the value of the magnetostriction constant. Therefore, if internal stresses are of the order of 10 3 MPa Žin agreement with Refs. w6,8,15x. and the magnetostriction constant is around 10y7 Žsuch value is expected for the investigated Co-rich composition., the second term of Eq. Ž1. is almost of the same order as the first one. This point can be of importance in the case of Co-rich composi-
tion with positive and nearly zero magnetostriction constant. The change of sign of magnetostriction constant under the effect of internal quenched-in stresses can be predicted in this case. Sample C showed drastic changes of the shape of hysteresis loop under external stress. This experimental fact can be used for technical application to design a magnetoelastic sensor. 4. Description of the sensor A magnetoelastic sensor of the level of a liquid essentially consists in a piece of the sample C surrounded by the
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
133
Acknowledgements A. Zhukov gratefully acknowledges the Gobierno Vasco for fellowship. The work has been supported by the Departamento de Industria del GV under project OD98UN27 and by the GV under project PI-1997-33. References
Fig. 3. Magnetoelastic sensor based on the change of hysteresis loop of sample C with tensile stresses.
primary and secondary coils Žsee Fig. 3.. The sample is loaded with approximately 10 g and therefore exhibits a flat hysteresis loop. The floating weight is attached to the lower end of the sample. When the liquid reaches the weight, the stress decreases giving rise to the appearance of the rectangular hysteresis loop. The principle of the sensor’s work is based on the change of the voltage of the secondary coil which increases drastically when the hysteresis loop of sample C becomes rectangular due to an essential decreasing of the stress. A simple circuit including the amplification of the signal and also an alarm set was used to detect changes of voltage in the secondary coil, which should be ascribed to the change of tensile stresses, as a consequence of the floating effect of the weight in the liquid.
5. Conclusions The following conclusions can be outlined. –The effect of external applied stresses on the hysteresis loops of the Co-rich microwires containing Mn or Fe–Ni has been investigated. –A small variation of Mn content significantly changes the external stress dependence of the switching field H U . In microwires with x s 10, H U increases with P, while for x s 8 H U decreases with P and MB finally disappears. –The observed H U Ž P . experimental dependencies were explained on the basis of stress and compositional dependence of the magnetostriction constant value in glass-coated microwires. –Drastic changes of hysteresis loop under the external stresses have been used to design a magnetoelastic sensor of the level of liquid.
w1x R. Gemperle, L. Kraus, J. Schneider, Magnetization reversal in amorphous ŽFe1y x Ni x .80P10 B10 microwires, Czech. J. Phys. B 28 Ž1978. 1138–1145. w2x A.P. Zhukov, M. Vazquez, J. Velazquez, H. Chiriac, V. Larin, The ´ ´ remagnetization process of thin and ultrathin Fe-rich amorphous wires, J. Magn. Magn. Mater. 151 Ž1995. 132–138. w3x J. Gonzalez, N. Murillo, V. Larin, J.M. Barandiaran, ´ ´ M. Vazquez, ´ A. Hernando, Magnetic bistability of glass-covered Fe-rich amorphous microwire: influence of heating treatments and applied tensile stress, Sens. Actuators, A 59 Ž1997. 97–100. w4x H. Chiriac, T.A. Ovari, Gh. Pop, Magnetic behavior of glass-covered amorphous wires, J. Magn. Magn. Mater. 157r158 Ž1996. 227–228. w5x M. Vazquez, A. Zhukov, Magnetic properties of glass-coated amor´ phous and nanocrystalline microwires, J. Magn. Magn. Mater. 160 Ž1996. 223–228. w6x S.A. Baranov, V.N. Berzhanski, S.K. Zotov, V.L. Kokoz, V.S. Larin, A.V. Torcunov, Ferromagnetic resonance in amorphous magnetic wires, Phys. Met. Metallogr. 67 Ž1989. 70–75. w7x J. Velazquez, M. Vazquez, A. Zhukov, Magnetoelastic anisotropy ´ ´ distribution in glass-coated microwires, J. Mater. Res. 11 Ž1996. 2499–2505. w8x H. Chiriac, T.A. Ovari, Gh. Pop, Internal stress distribution in glass-covered amorphous magnetic wires, Phys. Rev. B 52 Ž1995. 10104–10113. w9x C.F. Catalan, V.M. Prida, J. Alonso, M. Vazquez, A. Zhukov, B. ´ Hernando, J. Velazquez, Effect of glass-coating on magnetic proper´ ties of amorphous microwires, Mater. Sci. Eng. A, Supplement Ž1996. 463–466. w10x J. Gonzalez, N. Murillo, V. Larin, J.M. Barandiaran, M. Vazquez, ´ A. Hernando, Magnetic bistability of glass-covered Fe-rich amorphous microwire: influence of heating treatments and applied tensile stress, Sens. Actuators, A 29 Ž1997. 97–100. w11x P.Marin, J. Arcas, A. Zhukov, M. Vazquez, A. Hernando, in: G.C. ´ Hadjipanayis ŽEd.., Magnetic Hysteresis in Novel Magnetic Materials, Kluwer Academic Publishers, Netherlands, 1997, pp. 743–748. w12x J. Gonzalez, J.M. Blanco, M. Vazquez, J.M. Barandiaran, ´ ´ ´ G. Rivero, A. Hernando, Influence of the applied tensile stress on the magnetic properties of current annealed amorphous wires, J. Appl. Phys. 70 Ž1991. 6522–6524. w13x J.M. Barandiaran, A. Hernando, V. Madurga, O.V. Nielsen, M. Vazquez, M. Vazquez-Lopez, Temperature, stress, and structural-re´ ´ ´ laxation dependence of the magnetostriction in ŽCo 0.94 Fe 0.06 . 75Si 15 B10 glasses, Phys. Rev. B 35 Ž1987. 5066–5071. w14x J. Gonzalez, J.M. Blanco, A. Hernando, J.M. Barandiaran, M. ´ Vazquez, G. Rivero, Stress dependence of magnetostriction in amor´ phous ferromagnets: its variation with temperature and induced anisotropy, J. Magn. Magn. Mater. 114 Ž1992. 75–81. w15x A. Zhukov, M. Vazquez, J. Velazquez, A. Hernando, V. Larin, ´ ´ Magnetic properties of Fe-based glass-coated microwires, J. Magn. Magn. Mater. 170 Ž1997. 323–330.
Magnetoelastic sensor of liquid level based on magnetoelastic properties of Co-rich microwires A. Zhukov a
b,),1
, A.F. Cobeno ˜ a, J. Gonzalez b, J.M. Blanco a, P. Aragoneses a, L. Dominguez a
Departamento Fisica Aplicada I y Departamento de Electronica y Telecomunicaciones ´ ´ EUITI, UniÕersidad Paıs ´ Vasco, AÕda Felipe IV 1B, 20011, San Sebastian, Spain b Departamento Fisica de Materiales, Facultad de Quımica, UniÕersidad Paıs ´ ´ Vasco, 1072, 20080, San Sebastian, Spain
Abstract The effect of external tensile stress on the hysteresis loops of nearly-zero magnetostrictive glass-coated amorphous microwires of ŽCo 100yx Mn x . 0.75 Si 10 B15 Ž10 - x - 11. and Co 56.5 Fe 6.5 Ni 10 B l6 Si 11 compositions of metallic nucleus has been studied. All hysteresis loops have a rectangular shape without applied stress. Significant changes in the shape of the hysteresis loop are produced by the application of tensile stress, particularly the hysteresis loop of the sample ŽCo 92 Mn 8 . 75 Si 10 B15 under a loading of 10 g, becoming flat with reduced values of both remanence and coercivity. These changes of the hysteresis loop with the external strain have been used to design a magnetoelastic sensor of liquid level. q 2000 Elsevier Science S.A. All rights reserved. Keywords: Rectangular hysteresis loop; Switching field; Magnetoelastic energy
1. Introduction The well-known Žsince the 1960s. Taylor–Ulitovski method w1x has been recently employed for the preparation of tiny Žaround 20 mm in diameter. glass-coated amorphous microwires exhibiting magnetic bistability ŽMB. effect w2–4x. Recently, it has been found that these microwires exhibit MB even for very short samples and for nearly zero-magnetostrictive alloys w5x. On the other hand, microwires of compositions with negative magnetostriction do not exhibit MB, as a difference with respect to ‘commercial’ amorphous wires showing MB w5x. The observed peculiarities in the compositional dependence of MB, as well as the enhanced values of remanence were explained in terms of the additional stresses arising from the outer glass w5–8x. Depending on the thickness of glass coating, the switching field is at least one order of magnitude larger than that of melt-spun wires w2–4,7x. A nonhysteretic character of the magnetisation curves for negative magnetostriction compositions ŽCo 68.5Y2.5 Si 14.5 B 14.5 . was found
) 1
Corresponding author. On leave from the ‘AmoTec’, Kishinev, Moldova.
and explained in Refs. w5,9x taking into account the stresses arising from the glass coating. It was experimentally confirmed in Ref. w9x by the appearance of MB after glass removal in the alloy with initially nonhysteretic hysteresis loop. Only a few measurements of the effect of external tensile stresses on parameters of the hysteresis loops in a single Fe-rich composition were performed in Refs. w4,10x. No systematic study of Co-rich microwires with MB has been reported until now. In the case of the conventional Fe 75 B12.5 Si 15 amorphous wire with a diameter of 125 mm, the switching field H U is very sensitive to heat treatments and especially to applied stress w6,7,11,13x. It was found that the experimental dependence of H U on applied tensile stress s roughly follows a s 1r2 law for Fe-rich wires. Co-rich wires did not show such dependence. Consequently, a nucleation mechanism was invoked to explain the stress dependence of the switching field in Fe-rich wires and a propagation of domain walls—in Co-rich w12,13x. On the other hand, the effect of external stresses on the switching field is of special interest for the technical applications of these microwires. The aim of this work is to present and to analyse new data concerning the magnetic properties of Co-rich microwires, to study the effect
0924-4247r00r$ - see front matter q 2000 Elsevier Science S.A. All rights reserved. PII: S 0 9 2 4 - 4 2 4 7 Ž 9 9 . 0 0 1 5 2 - 1
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
130
Table 1 Compositions and labels of investigated samples Alloy
Label
Metallic nucleus radius rm Žmm.
Glass-coating thickness t Žmm.
Ratio r s trrm q t
ŽCo 89 Mn 11 . 0.75 Si 10 B15 ŽCo 89.5 Mn 10.5 . 0.75 Si 10 B15 ŽCo 90 Mn 10 . 0.75 Si 10 B15 Co 56.5 Fe 6.5 Ni 10 B l6 Si 11
A B C D
5.4 3.625 5 5
6 5.87 5.6 6.75
0.53 0.35 0.431 0.425
of external tensile stresses on their magnetic properties and also to assess them for technical applications.
2. Experimental Amorphous microwires of nominal compositions ŽCo 100y x Mn x . 75 Si 10 B 15 Ž x s 8, 9 and 10 . and Co 56.5 Fe 6.5 Ni 10 B l6 Si 11 of similar geometric dimensions Ždiameter of metallic nucleus and thickness of glass coating. were obtained by the Taylor–Ulitovski technique w1,2,6x Žsee details in Table 1.. This method essentially consists in drawing a Pyrex-like glass tube containing the molten metal into a wire. Introduction of the receiving bobbin w6x allows to obtain samples of a few kilometers in length. Pieces 12 cm in length have been used for magnetic measurements. The axial Mz –Hz hysteresis loop of the samples was obtained by means of a conventional induction method at 50 Hz with a possibility to measure the hysteresis loops under load, P, attached to the sample. It allows the
determination of the switching field, H U , and the ratio remanence to saturation magnetisation, m r . The magnetic field, Hz , was applied by a Helmholtz coil system with a maximum field of 5 kArm. More details on the experimental set-up can be found in Ref. w10x. Four different samples labelled A, B, C and D respectively have been investigated Žsee details in Table 1..
3. Experimental results and their discussion Fig. 1a–d show the axial hysteresis loops of all studied samples. All the samples exhibited a single and large Barkhausen jump. From Fig. 1A–C it can be noted that the switching field, H U , increases with x from 15 Arm at x s 10 up to 50 Arm at x s 11. The experimental dependencies of the switching field, H U , and remanence, m r , on external tensile strain are presented in Fig. 2. It is clear, that the curves H U Ž P . and m r Ž P . for samples A–C are quite different. H U is roughly stress-independent for small P and then starts to increase
Fig. 1. Axial hysteresis loops for both studied compositions of the microwires: ŽA., ŽB., ŽC. and ŽD., respectively.
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
in sample A. On the contrary, sample B first shows a slight increasing and then a decreasing of H U with P. Samples A and B always showed rectangular hysteresis loop. The sample C has a rectangular hysteresis at zero applied stress, although its switching field is rather small. With the increase in weight, P, H U and m r decreased and finally MB disappeared. The behaviour of sample D results to be quite similar to that of sample C, when H U decreases with P, but its hysteresis loop is still rectangular. These changes of hysteresis loops Žits shape, coercivity and remanence. under the effect of the external tensile stress can be explained from a stress dependence of the
131
magnetostriction constant. It is well known that in similar Co-rich compositions of amorphous alloys containing Fe, the magnetostriction constant changes in sign from positive to negative with increasing Co content w14,15x. It was found experimentally w12,13x that
l Ž s . s l Ž 0 . y Bs
Ž 1.
where lŽ0. is the saturation magnetostriction constant at zero applied stresses and B is a positive coefficient of the order of 10y1 0 MPa. The main difference between conventional wires and microwires is that the latter contain a glass coating. The
Fig. 2. Effect of the external stress on the critical field H U and the reduced remanence m r of samples A–D. The scales in the insets of Žb. and Žc. are the same for each figure.
132
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
Fig. 2 Žcontinued..
thermal expansion coefficients of metallic nucleus and glass coating are rather different. This difference introduces strong internal stresses one to two orders of magnitude larger than in the case of conventional wires. The existence of high quenched-in internal stresses seems to be able to change significantly the value of the magnetostriction constant. Therefore, if internal stresses are of the order of 10 3 MPa Žin agreement with Refs. w6,8,15x. and the magnetostriction constant is around 10y7 Žsuch value is expected for the investigated Co-rich composition., the second term of Eq. Ž1. is almost of the same order as the first one. This point can be of importance in the case of Co-rich composi-
tion with positive and nearly zero magnetostriction constant. The change of sign of magnetostriction constant under the effect of internal quenched-in stresses can be predicted in this case. Sample C showed drastic changes of the shape of hysteresis loop under external stress. This experimental fact can be used for technical application to design a magnetoelastic sensor. 4. Description of the sensor A magnetoelastic sensor of the level of a liquid essentially consists in a piece of the sample C surrounded by the
A. ZhukoÕ et al.r Sensors and Actuators 81 (2000) 129–133
133
Acknowledgements A. Zhukov gratefully acknowledges the Gobierno Vasco for fellowship. The work has been supported by the Departamento de Industria del GV under project OD98UN27 and by the GV under project PI-1997-33. References
Fig. 3. Magnetoelastic sensor based on the change of hysteresis loop of sample C with tensile stresses.
primary and secondary coils Žsee Fig. 3.. The sample is loaded with approximately 10 g and therefore exhibits a flat hysteresis loop. The floating weight is attached to the lower end of the sample. When the liquid reaches the weight, the stress decreases giving rise to the appearance of the rectangular hysteresis loop. The principle of the sensor’s work is based on the change of the voltage of the secondary coil which increases drastically when the hysteresis loop of sample C becomes rectangular due to an essential decreasing of the stress. A simple circuit including the amplification of the signal and also an alarm set was used to detect changes of voltage in the secondary coil, which should be ascribed to the change of tensile stresses, as a consequence of the floating effect of the weight in the liquid.
5. Conclusions The following conclusions can be outlined. –The effect of external applied stresses on the hysteresis loops of the Co-rich microwires containing Mn or Fe–Ni has been investigated. –A small variation of Mn content significantly changes the external stress dependence of the switching field H U . In microwires with x s 10, H U increases with P, while for x s 8 H U decreases with P and MB finally disappears. –The observed H U Ž P . experimental dependencies were explained on the basis of stress and compositional dependence of the magnetostriction constant value in glass-coated microwires. –Drastic changes of hysteresis loop under the external stresses have been used to design a magnetoelastic sensor of the level of liquid.
w1x R. Gemperle, L. Kraus, J. Schneider, Magnetization reversal in amorphous ŽFe1y x Ni x .80P10 B10 microwires, Czech. J. Phys. B 28 Ž1978. 1138–1145. w2x A.P. Zhukov, M. Vazquez, J. Velazquez, H. Chiriac, V. Larin, The ´ ´ remagnetization process of thin and ultrathin Fe-rich amorphous wires, J. Magn. Magn. Mater. 151 Ž1995. 132–138. w3x J. Gonzalez, N. Murillo, V. Larin, J.M. Barandiaran, ´ ´ M. Vazquez, ´ A. Hernando, Magnetic bistability of glass-covered Fe-rich amorphous microwire: influence of heating treatments and applied tensile stress, Sens. Actuators, A 59 Ž1997. 97–100. w4x H. Chiriac, T.A. Ovari, Gh. Pop, Magnetic behavior of glass-covered amorphous wires, J. Magn. Magn. Mater. 157r158 Ž1996. 227–228. w5x M. Vazquez, A. Zhukov, Magnetic properties of glass-coated amor´ phous and nanocrystalline microwires, J. Magn. Magn. Mater. 160 Ž1996. 223–228. w6x S.A. Baranov, V.N. Berzhanski, S.K. Zotov, V.L. Kokoz, V.S. Larin, A.V. Torcunov, Ferromagnetic resonance in amorphous magnetic wires, Phys. Met. Metallogr. 67 Ž1989. 70–75. w7x J. Velazquez, M. Vazquez, A. Zhukov, Magnetoelastic anisotropy ´ ´ distribution in glass-coated microwires, J. Mater. Res. 11 Ž1996. 2499–2505. w8x H. Chiriac, T.A. Ovari, Gh. Pop, Internal stress distribution in glass-covered amorphous magnetic wires, Phys. Rev. B 52 Ž1995. 10104–10113. w9x C.F. Catalan, V.M. Prida, J. Alonso, M. Vazquez, A. Zhukov, B. ´ Hernando, J. Velazquez, Effect of glass-coating on magnetic proper´ ties of amorphous microwires, Mater. Sci. Eng. A, Supplement Ž1996. 463–466. w10x J. Gonzalez, N. Murillo, V. Larin, J.M. Barandiaran, M. Vazquez, ´ A. Hernando, Magnetic bistability of glass-covered Fe-rich amorphous microwire: influence of heating treatments and applied tensile stress, Sens. Actuators, A 29 Ž1997. 97–100. w11x P.Marin, J. Arcas, A. Zhukov, M. Vazquez, A. Hernando, in: G.C. ´ Hadjipanayis ŽEd.., Magnetic Hysteresis in Novel Magnetic Materials, Kluwer Academic Publishers, Netherlands, 1997, pp. 743–748. w12x J. Gonzalez, J.M. Blanco, M. Vazquez, J.M. Barandiaran, ´ ´ ´ G. Rivero, A. Hernando, Influence of the applied tensile stress on the magnetic properties of current annealed amorphous wires, J. Appl. Phys. 70 Ž1991. 6522–6524. w13x J.M. Barandiaran, A. Hernando, V. Madurga, O.V. Nielsen, M. Vazquez, M. Vazquez-Lopez, Temperature, stress, and structural-re´ ´ ´ laxation dependence of the magnetostriction in ŽCo 0.94 Fe 0.06 . 75Si 15 B10 glasses, Phys. Rev. B 35 Ž1987. 5066–5071. w14x J. Gonzalez, J.M. Blanco, A. Hernando, J.M. Barandiaran, M. ´ Vazquez, G. Rivero, Stress dependence of magnetostriction in amor´ phous ferromagnets: its variation with temperature and induced anisotropy, J. Magn. Magn. Mater. 114 Ž1992. 75–81. w15x A. Zhukov, M. Vazquez, J. Velazquez, A. Hernando, V. Larin, ´ ´ Magnetic properties of Fe-based glass-coated microwires, J. Magn. Magn. Mater. 170 Ž1997. 323–330.