Microstructural Changes Influencing the Magnetoresistive Behavior of Bulk Nanocrystalline Materials

Wurster, Stefan; Stückler, Martin; Weissitsch, Lukas; Müller, Timo; Bachmaier, Andrea

doi:10.3390/app10155094

Cited by 12 publications

(7 citation statements)

References 39 publications

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“…Similar phase separation processes have already been observed in the Co-Cu system and have been attributed to spinodal decomposition [30]. The same seperation process could be responsible for the improved magnetoresistive behavior of annealed Cu-Co HPT-materials [31]. In the 600°C annealed sample, a demixed state is present with the highest coercivity and the smallest magnetic ξ 2 .…”

Section: Magnetic Force Microscopysupporting

confidence: 72%

On the magnetic nanostructure of a Co-Cu alloy processed by high-pressure torsion

Stückler,

Teichert,

Matković

et al. 2021

Preprint

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In this study, a preparation route of Co-Cu alloys with soft magnetic properties by high-pressure torsion deformation is introduced. Nanocrystalline, supersaturated single-phase microstructures are obtained after deformation of Co-Cu alloys, which are prepared from an initial powder mixture with Co-contents above 70 wt.%. Isochronal annealing treatments up to 400°C further reveal a remarkable microstructural stability. Only at 600°C, the supersaturated phase decomposes into two fcc-phases. The coercivity, measured by SQUID as a function of annealing temperature, remains significantly below the value for bulk-Co in all states investigated. In order to understand the measured magnetic properties in detail, a quantitative analysis of the magnetic microstructure is carried out by magnetic force microscopy and correlated to the observed changes in coercivity. Our results show that the

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Section: Magnetic Force Microscopysupporting

confidence: 72%

On the magnetic nanostructure of a Co-Cu alloy processed by high-pressure torsion

Stückler,

Teichert,

Matković

et al. 2021

Preprint

Self Cite

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“…2. Measurements were started after settling the target temperature for 15 min, since similarly processed Co-Cu samples showed the majority of microstructural changes happening only during a short time period after reaching the target temperature [7]. The time stamps of the measurements are represented by the black diamonds in fig.…”

Section: Resultsmentioning

confidence: 99%

In situ AC-hysteresis measurements of SPD-processed Cu20(Fe15Co85)80

Stückler,

Wurster,

Pippan

et al. 2021

Preprint

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The changes of magnetic properties upon heat treatment of a metastable supersaturated solid solution processed by severe plastic deformation are investigated by in-situ AC-hysteresis measurements. Data are analyzed in the framework of dynamic loss theory, with correlative investigations of the microstructural properties. The evolution of hysteresis upon annealing points out that the single-phase supersaturated solid solution remains stable up to 400 • C, then hindering of domain wall motion sets in at this temperature. At 600 • C, a multi phase microstructure is present, causing a significant increase in coercivity.

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“…For RT resistivity measurements within a magnetic field, the experimental setup described in [8,9] was used. Herein, GMR is represented by the difference in resistivity at zero field and highest field in relation to the resistivity at zero field.…”

Section: Methodsmentioning

confidence: 99%

“…IOP Publishing doi:10.1088/1757-899X/1249/1/012047 2 Typical methods to fabricate granular alloys are mechanical alloying, ion implantation, melt spinning and co-evaporation. It was already demonstrated that materials processed by high-pressure torsion (HPT), a severe plastic deformation technique, also show a GMR effect [7][8][9]. Fathoming the prospects of HPT together with a proper concatenation of annealing treatments, this work focuses on the granular GMR effect of a variety of ternary Cu-based materials.…”

Section: Introductionmentioning

confidence: 99%

Magnetoresistive behaviour of ternary Cu-based materials processed by high-pressure torsion

Kasalo

Wurster

Stückler

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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Severe plastic deformation using high-pressure torsion of ternary Cu-based materials (CuFeCo and CuFeNi) was used to fabricate bulk samples with a nanocrystalline microstructure. The goal was to produce materials featuring the granular giant magnetoresistance effect, requiring interfaces between ferro- and nonmagnetic materials. This magnetic effect was found for both ternary systems; adequate subsequent annealing had a positive influence. The as-deformed states, as well as microstructural changes upon thermal treatments, were studied using scanning electron microscopy and X-ray diffraction measurements. Deducing from electron microscopy, a single-phase structure was observed for all as-deformed samples, indicating the formation of a supersaturated solid solution. However, judging from the presence of the granular giant-magnetoresistive effect, small ferromagnetic particles have to be present. The highest drop in room temperature resistivity (2.45% at 1790 kA/m) was found in Cu62Fe19Ni19 after annealing for 1 h at 400 °C. Combining the results of classical microstructural studies and magnetic measurements, insights into the evolution of ferromagnetic particles are accessible.

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Microstructural Changes Influencing the Magnetoresistive Behavior of Bulk Nanocrystalline Materials

Cited by 12 publications

References 39 publications

On the magnetic nanostructure of a Co-Cu alloy processed by high-pressure torsion

On the magnetic nanostructure of a Co-Cu alloy processed by high-pressure torsion

In situ AC-hysteresis measurements of SPD-processed Cu20(Fe15Co85)80

Magnetoresistive behaviour of ternary Cu-based materials processed by high-pressure torsion

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