| 1. |
- Malmhall, Roger, et al.
(författare)
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Hall resistivity of a two-phase magnetic material - crystallised Metglas 2826
- 1979
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Ingår i: Journal of Physics F: Metal Physics. - : Institute of Physics (IOP). - 0305-4608. ; 9:2, s. 317-325
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Tidskriftsartikel (refereegranskat)abstract
- Hall resistivity measurements in the temperature range 100-800 K have been used to study the influence of thermal cycling and annealing on amorphous Fe40Ni40P14B6. While the as-received sample has Tc = 510 K. thermal cycling to 700 K yields a two-phase system. one of the phases having a broad transition around 425 K. Annealing for three hours at 800 K causes this transition to sharpen up. and we also observe a second transition at 730 K. The extraordinary Hall coefficient (R1) has been analysed and is described in terms of linear contributions from each phase. From simultaneous measurements of the ohmic resistivity ρ on the same sample it is found that, for the two-phase material. R1 is related to ρ as R1 = aρ + bρ2 for 100 < K < 300 K. In the amorphous state there is an anomaly in ρ at Tc. From the relationship between R1(T) and ρ(T) it is concluded that in both amorphous and crystallised materials the side jump is of the same order of magnitude as in dilute Fe alloys.
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| 2. |
- Malmhäll, Roger, et al.
(författare)
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Compositional short-range-order effects in the Hall resistivity of amorphous Fe27Ni53P14B6
- 1979
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 50:B11, s. 7656-7658
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Tidskriftsartikel (refereegranskat)abstract
- Hall resistivity ( ρH) studies confirm that the Curie temperature (Tc) can be varied reproducibly between 374 K and 368 K by suitably annealing the alloy at 250 °C and 300 °C respectively. This is explained as being due to changes in compositional short‐range‐order. The calculated magnetic susceptibility, obtained from the temperature dependence of ρH, shows a strong fluctuation contribution described by (T−Tc)−γ, with γ=1.54±0.04 in both cases. A significant contribution to the temperature dependence of the ohmic resistivity, which is also uneffected by the annealing conditions, is found to be of magnetic origin.
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| 3. |
- Malmhäll, Roger, et al.
(författare)
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Hall resistivity of a magnetic amorphous alloy : Effects of thermal cycling and annealing
- 1978
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 28:2, s. 159-176
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the effects of thermal cycling and annealing on the Hall resistivity ρH and electrical resistivity ρ of an amorphous magnetic material, Metglas 2826A. Thermal cycling up to 600 K has no significant effect on ρ but changes ρH, especially at T > 300 K. Annealing at higher temperatures Ta affects ρH more strongly than it influences ρ. For Ta = 650 K the Curie temperature jumps by ∼ 300 K and this, combined with X-ray data, is regarded as being symptomatic of the onset of crystallization. It is demonstrated that, for a fixed T, the variation of the extraordinary Hall coefficient R1 is simple correlated with that of ρ for both the amorphous material and the annealed (crystallized) specimens. Furthermore, for a given Ta, the variations of R1 and ρ as functions of temperature exhibit the same formal relationship. The temperature dependence of ρ in the annealed specimens is rendered plausible in terms of recent theories of disordered materials. Room-temperature studies of electron spin resonance and the field dependence of the magnetization are also reported.
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| 4. |
- Malmhäll, Roger, et al.
(författare)
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Hall resistivity of Fe and Fe-Ni based amorphous alloys
- 1978
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Ingår i: Rapidly Quenched Metals III. - 0904357228 ; , s. 145-148
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Konferensbidrag (refereegranskat)abstract
- We report on Hall and ohmic studies of Fe and Fe-Ni based magnetic Metglas alloys in the temperature range 100-700 K and in magnetic fields up to 2.5 Tesla. While the saturation magnetization and the Curie temperature in these systems vary significantly, it is found that the extraordinary Hall coefficient, R1, at 300 K is almost a constant. While the temperature coefficient of the ohmic resistivity ρ is generally positive, dR1/dT is found to be of either sign. A cusp is observed in R1 and in dρ/dT for some of the alloys.
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| 5. |
- Malmhäll, Roger, et al.
(författare)
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Metglas 2826B—Transport, magnetic and thermal properties
- 1978
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 49:3, s. 1727-1729
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Tidskriftsartikel (refereegranskat)abstract
- We report Hall resistivity, magnetization, heat capacity, and electrical resistivity studies on Metglas2826B (Fe29Ni49P14B6Si2) spanning the temperature regime 77 to 800K. The critical exponents for this system are found to be β = 0.40 ± 0.01, δ = 5.25 ± 0.10, and γ = 1.7 ± 0.1. The magnetic isotherms fit into universal scaling functions over a rather wide range of temperature both above and below Tc. The specific heat exhibits a sharp peak at Tc. The temperature derivative of the electrical resistivity has a marked change at Tc. Although Tc increases slightly on thermal cycling to higher temperatures, the critical exponents are not influenced by this.
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| 6. |
- Malmhäll, Roger, et al.
(författare)
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Transport properties of amorphous ferromagnets : Hall and ohmic resistivities
- 1979
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Ingår i: Physica status solidi. A, Applied research. - : John Wiley & Sons. - 0031-8965 .- 1521-396X. ; 53:2, s. 641-651
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous measurements are made of the ohmic resistivity (ϱ) and the Hall resistivity (ϱH) of a number of amorphous ferromagnetic Fe–Ni based alloys prepared by the rapid quenching technique. The temperature range of the experiments is 100 through 700 K and the applied magnetic fields are varied up to 2.5 T. It turns out that for all the amorphous alloys: (i) R1 ≈ 5 × 10−8 m3/As, (ii) ϱ ≈ 1.5 μΩm, (iii) ϱH has a sharp drop from which the ferromagnetic transition temperature (TC) can be determined to ≈ 5 K, (iv) the critical exponent γ ≈ 1.6 for (TC + 1) < < T < (TC + 50) K, and (v) the extraordinary Hall conductivity γHs is of the same order (≈ 5 × 104 Ω−1 m−1) as in crystalline Fe alloys. Further, in some cases (dϱ/dT) exhibits a well-defined anomaly at TC.
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| 7. |
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