Upna Madurga
Professor of Condensed Matter Physics. Honorary Professor at Public University of Navarre. Spain. Depto. de Física, Física y Tecnología de Materiales. Campus Arrosadia s/n. 31006 Pamplona. España. e-mail: [email protected]
Address: Spain
Address: Spain
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processes were performed: normal deposition and off-normal. After annealing in an inert atmosphere, in-plane isotropic magnetic hysteresis loops were measured for the normal deposited films. In contrast, in-plane anisotropic hysteresis loops were obtained from the off-normal deposited ones. An in-plane easy direction for the magnetisation, perpendicular to the incidence plane of the plasma during deposition, was measured with an anisotropy field of ≈100 Oe and an easy coercive field of ≈24 Oe. The mechanical behaviour of the magnetically anisotropic coated micro-cantilevers
and their response to a decreasing temperature permitted observing the martensitic transformation of the Ni2MnGa thin films.
c ≈ 0.94 for pure Fe. Their isotropic magnetostriction coefficient, ks, was also determined. From pure Co to 30 at.% Fe ks values were similar to those corresponding to the crystalline alloys: from pure Co to 4 at.% Fe was negative and of the order of 10-6; ks increased to 10-5 up to 25 at.% Fe and achieved 10-4 from 30 at.% Fe to 90 at.% Fe; ks decreased to 10-5 for pure Fe. A chemical short-range order
between the Co atoms surrounded by the Fe ones, increasing the magnetic moment of Fe atoms, was used to explain the observed behavior.
anisotropy in the films. The width of the nano-strings was controlled between 8 and 30 nm by selecting the off-
normal deposition parameters. Two sets of coated MCTV were produced: ones with nano-strings parallel to the
longitudinal symmetry axis of the MCTV and other ones with the nano-strings perpendicular to this axis. The
morphological anisotropy present in the Co film was also reflected in a mechanical anisotropy in the MCTVS. For
MCTVS coated with longitudinal nano-strings, the frequency of the mechanical resonance decreased ≈1.5% with respect to the non-coated ones, while it decreased ≈3% for coated MCTVS with transversal nano-strings. This was explained in terms of the anisotropic elastic properties of the Co films. The extra changes of the frequency of the
mechanical resonance produced by a magnetic field applied to the MCTV were discussed in considering also the
magnetic anisotropy of the films.
angle q, were observed. q changed with t from ≈ 17 deg. to ≈ 25 deg., presenting an intermediate sharp maximum that has not been described before. The reduced length of the zigzag walls also exhibited a peak at t ≈ 70 nm. The relationship between the total reduced length and the
density energy of the magnetic wall allowed us to establish a change from a Néel-type to a Bloch-type core of the zigzag walls at this thickness, t ≈ 70 nm. We also accounted for the
magnetic energy arising from the surface roughness of the thinner films after imaging the film surface morphologies. Moreover, this distinctive behaviour of the zigzag walls of these low-anisotropy films was compared to that of high-anisotropy films.
glancing-angle deposition technique. A controlled easy direction of magnetisation (anisotropy field
μoHk ≈ 0.1 T) in the longitudinal or in the transverse direction of the micro-cantilevers was
generated. The mechanical properties of the films under the action of a magnetic field were opposite
depending on the magnetisation’s easy direction: i) their deflection was either zero or the maximum
value depending on the direction of the applied magnetic field with respect to the parallel or
transverse easy direction of magnetisation; ii) the shift in the resonance frequency under a
longitudinal or transverse magnetic field was also different depending on the longitudinal or
transverse easy direction of magnetisation. The use of these coated devices with micromagnet-like
films for sensors and transducers is discussed.
processes were performed: normal deposition and off-normal. After annealing in an inert atmosphere, in-plane isotropic magnetic hysteresis loops were measured for the normal deposited films. In contrast, in-plane anisotropic hysteresis loops were obtained from the off-normal deposited ones. An in-plane easy direction for the magnetisation, perpendicular to the incidence plane of the plasma during deposition, was measured with an anisotropy field of ≈100 Oe and an easy coercive field of ≈24 Oe. The mechanical behaviour of the magnetically anisotropic coated micro-cantilevers
and their response to a decreasing temperature permitted observing the martensitic transformation of the Ni2MnGa thin films.
c ≈ 0.94 for pure Fe. Their isotropic magnetostriction coefficient, ks, was also determined. From pure Co to 30 at.% Fe ks values were similar to those corresponding to the crystalline alloys: from pure Co to 4 at.% Fe was negative and of the order of 10-6; ks increased to 10-5 up to 25 at.% Fe and achieved 10-4 from 30 at.% Fe to 90 at.% Fe; ks decreased to 10-5 for pure Fe. A chemical short-range order
between the Co atoms surrounded by the Fe ones, increasing the magnetic moment of Fe atoms, was used to explain the observed behavior.
anisotropy in the films. The width of the nano-strings was controlled between 8 and 30 nm by selecting the off-
normal deposition parameters. Two sets of coated MCTV were produced: ones with nano-strings parallel to the
longitudinal symmetry axis of the MCTV and other ones with the nano-strings perpendicular to this axis. The
morphological anisotropy present in the Co film was also reflected in a mechanical anisotropy in the MCTVS. For
MCTVS coated with longitudinal nano-strings, the frequency of the mechanical resonance decreased ≈1.5% with respect to the non-coated ones, while it decreased ≈3% for coated MCTVS with transversal nano-strings. This was explained in terms of the anisotropic elastic properties of the Co films. The extra changes of the frequency of the
mechanical resonance produced by a magnetic field applied to the MCTV were discussed in considering also the
magnetic anisotropy of the films.
angle q, were observed. q changed with t from ≈ 17 deg. to ≈ 25 deg., presenting an intermediate sharp maximum that has not been described before. The reduced length of the zigzag walls also exhibited a peak at t ≈ 70 nm. The relationship between the total reduced length and the
density energy of the magnetic wall allowed us to establish a change from a Néel-type to a Bloch-type core of the zigzag walls at this thickness, t ≈ 70 nm. We also accounted for the
magnetic energy arising from the surface roughness of the thinner films after imaging the film surface morphologies. Moreover, this distinctive behaviour of the zigzag walls of these low-anisotropy films was compared to that of high-anisotropy films.
glancing-angle deposition technique. A controlled easy direction of magnetisation (anisotropy field
μoHk ≈ 0.1 T) in the longitudinal or in the transverse direction of the micro-cantilevers was
generated. The mechanical properties of the films under the action of a magnetic field were opposite
depending on the magnetisation’s easy direction: i) their deflection was either zero or the maximum
value depending on the direction of the applied magnetic field with respect to the parallel or
transverse easy direction of magnetisation; ii) the shift in the resonance frequency under a
longitudinal or transverse magnetic field was also different depending on the longitudinal or
transverse easy direction of magnetisation. The use of these coated devices with micromagnet-like
films for sensors and transducers is discussed.