Spin correlations and magnetic order in Co-Ga alloys: A comprehensive study

Yasin, Sk Mohammad; Saha, Ritwik; Srinivas, V.; Kasiviswanathan, S.; Nigam, A. K.

doi:10.1016/j.jallcom.2015.07.072

Cited by 11 publications

(5 citation statements)

References 29 publications

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“…The behavior of the calculated magnetic properties agrees well with the results of reported experiments [14,23,43],in particular, for x < 0.1 where the onset of ferromagnetism was observed at x ≈ 0.07. The reported spin glass type property at lower Co concentration might be related to the localized magnetic moment of the excess Co atoms, due to the replacement of Ga on the 1a position.…”

Section: From Half To Full Co Contentsupporting

confidence: 89%

“…It should be mentioned that the Curie temperatures for f cc and hcp Co are nearly identical (difficult to distinguish in Figure 11). At about 1550 K, the calculated mean field Curie temperature of Co is approximately 10% higher, compared to the experimental value of ≈ 1400 K. The mean field values of the high moment states in the vicinity of x = 0.2 are similar to the experimental values reported in References [ [25,42,43]]. Such deviations may be caused by partial disorder in the samples [44,45] that was not accounted for in the present calculations.…”

Section: From Half To Full Co Contentsupporting

confidence: 75%

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Discontinuity in the Electronic Structure and Magnetic Order of β-Co1+xGa1-x

Fecher¹

2022

Preprint

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The present work reports on the calculated electronic and magnetic structure of the binary Co-Ga system at high Co content. β-CoGa adopts a simple cubic CsCl type structure. Well-ordered CoGa does not exhibit collective magnetism but is a paramagnetic, metallic compound. Neither Co nor Ga deficiency induces magnetic order, however, ferromagnetism is observed for Co-Ga anti-site disorder. The magnetic moment per cell increases up to about 1.2 μB in the completely disordered body centered cubic structure. With increasing Co content, Co1+xGa1−x maintains the CsCl type structure and becomes ferromagnetic. Most important, a discontinuity of the magnetic order with composition is observed at about 10% excess Co, where a change from a low magnetic moment state to a high moment state is observed. This is accompanied by a change in the electronic structure and transport properties. The discontinuity is forced by the increasing exchange splitting related to the localized moment of the additional Co atoms that replace Ga. Subsequently, the magnetic moment increases continuously up to 2.5 μB for x=0.6. For x≳0.6, the structure changes to face centered cubic with random site occupation and the magnetic moment further increases. Above the magnetic discontinuity, the Curie temperature increases linearly with the Co content from the onset of ferromagnetism, until it reaches its maximum in pure Co.

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Section: From Half To Full Co Contentsupporting

confidence: 89%

Section: From Half To Full Co Contentsupporting

confidence: 75%

Discontinuity in the Electronic Structure and Magnetic Order of β-Co1+xGa1-x

Fecher¹

2022

Preprint

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“…In this compositional range, the Curie temperature is very small (below 5 K) and changes discontinuously to 90 K at x = 0.1. The behavior of the calculated magnetic properties agrees well with the results of reported experiments [14,23,44], in particular, for x < 0.1 where the onset of ferromagnetism was observed at x ≈ 0.07. The reported spin glass type property at lower Co concentration might be related to the localized magnetic moment of the excess Co atoms, due to the replacement of Ga on the 1a position.…”

Section: From Half To Full Co Content: From Coga To Cosupporting

confidence: 89%

“…It should be mentioned that the Curie temperatures for f cc and hcp Co are nearly identical (difficult to distinguish in Figure 11). At about 1550 K, the calculated mean field Curie temperature of Co is approximately 10% higher, compared to the experimental value of ≈1400 K. The mean field values of the high moment states in the vicinity of x = 0.2 are similar to the experimental values reported in references [25,43,44]. Such deviations may be caused by partial disorder in the samples [45,46] that was not accounted for in the present calculations.…”

Section: From Half To Full Co Content: From Coga To Cosupporting

confidence: 71%

Discontinuity in the Electronic Structure and Magnetic Order of β-Co1+xGa1−x

Fecher

2022

Materials

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The present work reports on the calculated electronic and magnetic structure of the binary Co-Ga system at high Co content. β-CoGa adopts a simple cubic CsCl type structure. Well-ordered CoGa does not exhibit collective magnetism but is a paramagnetic, metallic compound. Neither Co nor Ga deficiency induces magnetic order; however, ferromagnetism is observed for Co-Ga anti-site disorder. The magnetic moment per cell increases by up to approximately 1.2 μB in the completely disordered body-centered cubic structure. With increasing Co content, Co1+xGa1−x maintains the CsCl type structure and becomes ferromagnetic. Most importantly, a discontinuity of the magnetic order with composition is observed at about 10% excess Co, where a change from a low magnetic moment state to a high moment state is observed. This is accompanied by a change in the electronic structure and transport properties. The discontinuity is forced by the increasing exchange splitting related to the localized moment of the additional Co atoms that replace Ga. Subsequently, the magnetic moment increases continuously up to 2.5 μB for x=0.6. For x≳0.6, the structure changes to a face-centered cubic structure with random site occupation and the magnetic moment further increases. Above the magnetic discontinuity, the Curie temperature increases linearly with the Co content from the onset of ferromagnetism, until it reaches its maximum in pure Co.

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“…9,10 Further, the magnetic phase diagram suggests the presence of a range of magnetic phases, such as, cluster spin glass to ferromagnetic (FM) state with small variations in composition. 11 On the other hand, earlier reports on electrical resistivity present a qualitative study over a wide range of temperature. A significant change in resistivity and temperature coefficient of resistivity (TCR) values especially in low temperature regime has been reported.…”

Section: Introductionmentioning

confidence: 99%

Giant magnetoresistance in the cluster glass regime of Co-Ga alloys

Yasin

Saha²,

Srinivas³

et al. 2016

AIP Advances

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A detailed study of low temperature electrical transport properties of CoxGa100−x (x = 54, 55.5, 57) alloy has been carried out. The origin of the resistivity anomalies and correlation between magnetic and electrical transport properties are identified through an elaborate analysis. The weak localization and enhanced electron-electron interaction effects partially support the electrical transport properties of the system. Further, the observed magnetoresistance can be well represented by localized model along with quantum corrections. The low temperature magnetoresistance value near critical composition is comparable to that reported in giant magnetoresistance materials.

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Spin correlations and magnetic order in Co-Ga alloys: A comprehensive study

Cited by 11 publications

References 29 publications

Discontinuity in the Electronic Structure and Magnetic Order of β-Co<sub>1+x</sub>Ga<sub>1</sub>-<sub>x</sub>

Discontinuity in the Electronic Structure and Magnetic Order of β-Co<sub>1+x</sub>Ga<sub>1</sub>-<sub>x</sub>

Discontinuity in the Electronic Structure and Magnetic Order of β-Co1+xGa1−x

Giant magnetoresistance in the cluster glass regime of Co-Ga alloys

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