| 1. |
- Alouhmy, M., et al.
(författare)
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Effects of carbon implantation on the low temperature magnetism behavior in amorphous Fe93Zr7 films
- 2022
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Ingår i: Materials Science & Engineering. - : Elsevier. - 0921-5107 .- 1873-4944. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- We present a detailed investigation on the effects of C-implantation on low temperature magnetic behavior in Fe93Zr7 amorphous films using spin wave theory, law of approach to saturation, and Alben and Becker's theory. Significant increase in Curie temperature with a decrease in coercivity were observed upon C-implantation. Bloch's law was used to analyze the temperature dependence of magnetization, and several important param-eters were extracted such as the stiffness constant of the spin wave, and the exchange constant. The local random anisotropy constant decreases from 0.35 to 0.19 MJ/m(3) with increasing carbon concentration from 0 to 11%. The ferromagnetic correlation length for which the anisotropy directions are assumed to be arbitrarily oriented in-creases significantly with increasing carbon content. By the use of the theory of Alben and Becker, we also extracted the local anisotropy from coercivity, and reasonable agreement was found with random magnetic anisotropy approach.
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| 2. |
- Alouhmy, M., et al.
(författare)
-
Effects of hydrogen implantation on the magnetocaloric properties of amorphous FeZr films
- 2021
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Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- We report on the effects of H-implantation on the magnetic and magnetocaloric properties of amorphous FeZr films. Arrott plots reveal a second order ferromagnetic to paramagnetic phase transition for the as-grown and H-implanted films, with an increase in T-C from 160 to 200 K upon implantation. The maximum change in magnetic entropy (-Delta S-M) increases from 0.66 to 0.77J/kgK for a field change mu 0 Delta H = 1.5T, as well as the relative cooling power (RCP) values were improved from 84.5 to 108.6J/kg. This improvement was attributed to the increase in magnetization and chemical inhomogeneity induced by the implantation process. The increase in the chemical inhomogeneity was supported by the determination of the local exponent n extracted from the slope of Ln(-Delta S-M) as a function of Ln(mu 0H), which is line with the simulated depth profile of hydrogen atoms through the FeZr film.
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| 3. |
- Alouhmy, M., et al.
(författare)
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Random magnetic anisotropy approach in amorphous Fe88.4Zr11.6 films : Effects of hydrogen implantation
- 2021
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 566
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Tidskriftsartikel (refereegranskat)abstract
- The effects of hydrogen implantation on the magnetic properties in amorphous Fe88.4Zr11.6Hx films with different hydrogen contents (0≤ x≤16) were investigated. The Curie temperature increases with increasing hydrogen content while the coercivity presents an important decrease upon H implantation. Based on the analysis of the approach to saturation in magnetization, the local random anisotropy constant KL was extracted. The local random anisotropy constant decreases from 1.468 MJ/m3 to 0.667 MJ/m3 when the concentration of H increases from 0 to 16%. The ferromagnetic correlation length was found to significantly increase with increasing hydrogen content. The local anisotropy was also extracted from the coercivity based on the Alben and Becker theory, which fits reasonably with that obtained using random magnetic anisotropy approach.
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| 4. |
- Charkaoui, A., et al.
(författare)
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Critical behavior and magnetocaloric effect in C -implanted Fe93Zr7 amorphous films
- 2020
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; , s. 316-317
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Tidskriftsartikel (refereegranskat)abstract
- We report on the effect of carbon ion-implantation on the critical behavior of Fe93Zr7 amorphous films. Both the as-grown and carbon-implanted Fe93Zr7 samples exhibit a second order ferromagnetic to paramagnetic transition. The critical exponents were investigated through different techniques such as modified-Arrott plot, the critical isotherm analysis and the Windom scaling relation. Analysis of the critical behavior was presented in terms of the magnetocaloric effect around TC. While there is a significant increase of the magnetization and TC upon C-implantation, the critical exponents were only slightly affected by implantation and were in line with those of the 3D-Heisenberg model.
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| 5. |
- Moubah, Reda, et al.
(författare)
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Enhanced magnetocaloric properties of FeZr amorphous films by C ion implantation
- 2016
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Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 175, s. 5-8
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Tidskriftsartikel (refereegranskat)abstract
- For a high magnetic refrigeration efficiency, a large change of magnetic entropy (-Delta S-M) associated with a high relative cooling power (RCP) are highly desirable. Here, the ion implantation is used to enhance both parameters in FeZr amorphous films. A considerable enhancement of both (-Delta S-M) and RCP, from 0.66 to 1.01 J/kg K and 84.5 to 155.5 J/kg respectively, for the as-grown sample compared to the C -implanted sample is obtained for a magnetic field change of mu(0)Delta H = 1.5 T. The increase of (-Delta S-M) and RCP values, are attributed to the increase of the magnetization and the chemical inhomogeneity, respectively upon C implantation.
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