Transition-metal granular solids: Microstructure, magnetic properties, and giant magnetoresistance

Wang, Jianqing; Xiao, Gang

doi:10.1103/physrevb.49.3982

Cited by 234 publications

(127 citation statements)

References 37 publications

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“…This is the expected behavior in the absence of magnetic interaction between magnetic clusters. 30 However, at high fields the curves for the M phase show a clear tendency to deviate from the linear behavior. A similar deviation has previously been observed in heterogeneous alloys and it has been attributed to the progressive field alignment of the disordered spins at the boundaries of the magnetic clusters, which causes a large variation of the MR compared with the corresponding change in magnetization.…”

Section: Discussionmentioning

confidence: 96%

Martensitic transition and magnetoresistance in a Cu-Al-Mn shape-memory alloy: Influence of ageing

et al. 2002

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We have studied the effect of ageing within the miscibility gap on the electric, magnetic, and thermodynamic properties of a nonstoichiometric Heusler Cu-Al-Mn shape-memory alloy, which undergoes a martensitic transition from a bcc-based structure (␤ phase͒ towards a close-packed structure (M phase͒. Negative magnetoresistance that shows an almost linear dependence on the square of magnetization with different slopes in the M and ␤ phases was observed. This magnetoresistive effect has been associated with the existence of Mn-rich clusters with the Cu 2 AlMn structure. The effect of an applied magnetic field on the martensitic transition has also been studied. The entropy change between the ␤ and M phases shows negligible dependence on the magnetic field, but it decreases significantly with annealing time within the miscibility gap. Such a decrease is due to the increasing amount of Cu 2 MnAl-rich domains that do not transform martensitically.

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Section: Discussionmentioning

confidence: 96%

Martensitic transition and magnetoresistance in a Cu-Al-Mn shape-memory alloy: Influence of ageing

et al. 2002

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“…10 The sign of the EHE is also dependent on the material type: Cu-Co, Fe-Ag, Fe-Au have positive values of EHE while Co-Ag has negative values. 3 Comparison was made in the thickness dependence of magneto-transport properties. As for the GMR effect, initial study from a series of Cu 80 Co 20 films was carried out and apparent similar thickness dependence on the thickness as Ag-based films was reported.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3][4][5] The magneto-transport properties generally can be separated into longitudinal part and transverse part. The longitudinal resistivity corresponds to the giant magnetoresistance ͑GMR͒ effect, 1,2 which has drawn much attention.…”

Section: Introductionmentioning

confidence: 99%

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Thickness dependence of magneto-transport in Cu-Co granular thin films

Wang

Dao

Kim

et al. 2004

Journal of Applied Physics

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This work explores the thickness dependence of magneto-transport properties in Cu 80 Co 20 granular thin films with different thickness. These results are compared with silver-based film series studied earlier. It was observed that the thickness dependence of the GMR effect was sensitive to the surface chemistry of the films. The extraordinary Hall effect ͑EHE͒ in these films was measured and found to be different from the Ag-based system. In the Cu-based system, the EHE is a weak function of film thickness over the range studied. When the variation of the spontaneous magnetization is taken into account the effective EHE has a universal thickness dependence.

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“…This behavior can be ascribed to various factors, such as the exhibition of martensite-austenite a ! c phase transition in Fe which is known to occur around 900 K, 32,33 interaction between the Fe cluster, 40,41 and due to the presence of inhomogeneities such as Cu impurities in Fe. Again we will discuss this point later in context with the analysis of the annealed sample.…”

Section: B Magnetic Propertiesmentioning

confidence: 99%

Experimental investigation of inhomogeneities, nanoscopic phase separation, and magnetism in arc melted Fe-Cu metals with equal atomic ratio of the constituents

Jaffari

Aftab²,

Anjum

et al. 2015

Journal of Applied Physics

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Composition gradient and phase separation at the nanoscale have been investigated for arc-melted and solidified with equiatomic Fe-Cu. Diffraction studies revealed that Fe and Cu exhibited phase separation with no trace of any mixing. Microscopy studies revealed that immiscible Fe-Cu form dense bulk nanocomposite. The spatial distribution of Fe and Cu showed existence of two distinct regions, i.e., Fe-rich and Cu-rich regions. Fe-rich regions have Cu precipitates of various sizes and different shapes, with Fe forming meshes or channels greater than 100 nm in size. On the other hand, the matrix of Cu-rich regions formed strips with fine strands of nanosized Fe. Macromagnetic response of the system showed ferromagnetic behavior with a magnetic moment being equal to about 2.13 μB/Fe atom and a bulk like negligible value of coercivity over the temperature range of 5–300 K. Anisotropy constant has been calculated from various laws of approach to saturation, and its value is extracted to be equal to 1350 J/m3. Inhomogeneous strain within the Cu and Fe crystallites has been calculated for the (unannealed) sample solidified after arc-melting. Annealed sample also exhibited local inhomogeneity with removal of inhomogeneous strain and no appreciable change in magnetic character. However, for the annealed sample phase separated Fe exhibited homogenous strain.

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Transition-metal granular solids: Microstructure, magnetic properties, and giant magnetoresistance

Cited by 234 publications

References 37 publications

Martensitic transition and magnetoresistance in a Cu-Al-Mn shape-memory alloy: Influence of ageing

Martensitic transition and magnetoresistance in a Cu-Al-Mn shape-memory alloy: Influence of ageing

Thickness dependence of magneto-transport in Cu-Co granular thin films

Experimental investigation of inhomogeneities, nanoscopic phase separation, and magnetism in arc melted Fe-Cu metals with equal atomic ratio of the constituents

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