Magnetoresistivity model and ionization‐energy approximation for ferromagnets

Arulsamy, Andrew Das; Cui, Xiangyuan; Stampfl, Catherine; Ratnavelu, Kuru

doi:10.1002/pssb.200844476

Cited by 23 publications

(52 citation statements)

References 39 publications

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“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Herein, however, we do not study exotic oxides such as cuprates and manganites, which have been discussed elsewhere with respect to oxygen-deficient normal state conductivity and ferromagnetism. [24,25] Apart from these applications, specially coated a-Fe 2 O 3 (for biostability) is also used in the fields of biomedical and bioengineering, such as for drug and protein delivery, and for cell separation and detoxification of biological fluids due to its magnetic properties. [26][27][28][29][30][31] In this case, the existence of Fe 2 + and Fe 3 + in a-FeO due to oxygen vacancies (x) may improve its magnetic properties as it resembles the ferrimagnetic Fe 3 O 4 , which also contains the mixed iron valence.…”

Section: Introductionmentioning

confidence: 99%

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Reversible Carrier‐Type Transitions in Gas‐Sensing Oxides and Nanostructures

et al. 2010

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Despite many important applications of α-Fe(2)O(3) and Fe doped SnO(2) in semiconductors, catalysis, sensors, clinical diagnosis and treatments, one fundamental issue that is crucial to these applications remains theoretically equivocal--the reversible carrier-type transition between n- and p-type conductivities during gas-sensing operations. Herein, we present an unambiguous and rigorous theoretical analysis in order to explain why and how the oxygen vacancies affect the n-type semiconductors α-Fe(2)O(3) and Fe-doped SnO(2), in which they are both electronically and chemically transformed into a p-type semiconductor. Furthermore, this reversible transition also occurs on the oxide surfaces during gas-sensing operation due to physisorbed gas molecules (without any chemical reaction). We make use of the ionization energy theory and its renormalized ionic displacement polarizability functional to reclassify, generalize and explain the concept of carrier-type transition in solids, and during gas-sensing operation. The origin of such a transition is associated with the change in ionic polarizability and the valence states of cations in the presence of oxygen vacancies and physisorped gas molecules.

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Section: Introductionmentioning

confidence: 99%

“…Sometimes, these analysis can be made quantitative with remarkable agreement with the experimental results. [25] We can now revisit the p-to-n-type transition occurring on the oxygen adsorbed on the a-Fe 2 O 3 surface. Contrary to ref.…”

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confidence: 99%

Reversible Carrier‐Type Transitions in Gas‐Sensing Oxides and Nanostructures

et al. 2010

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“…To calculate the polarizability and the adatom diffusion rates on a given substrate, we start from the dressed phonon frequency, which is given by [26,27] …”

Section: A Many-body Hamiltonianmentioning

confidence: 99%

“…Here, n 0 and E 0 F are the respective carrier density and the Fermi level or the highest occupied energy level for QDs, both at T = 0. Furthermore, k and K s are the wavenumber and the Thomas-Fermi wavenumber, respectively [26,27]. The exponential term in Eq.…”

Section: A Many-body Hamiltonianmentioning

confidence: 99%

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Diffusivity of adatoms on plasma-exposed surfaces determined from the ionization energy approximation and ionic polarizability

Arulsamy¹,

Ostrikov²

2009

Physics Letters A

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Microscopic surface diffusivity theory based on atomic ionization energy concept is developed to explain the variations of the atomic and displacement polarizations with respect to the surface diffusion activation energy of adatoms in the process of self-assembly of quantum dots on plasma-exposed surfaces. These polarizations are derived classically, while the atomic polarization is quantized to obtain the microscopic atomic polarizability. The surface diffusivity equation is derived as a function of the ionization energy. The results of this work can be used to fine-tune the delivery rates of different adatoms onto nanostructure growth surfaces and optimize the low-temperature plasma based nanoscale synthesis processes.

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Electron-Conduction Mechanism and Specific Heat Above Transition Temperature in LaFeAsO and BaFe2As2 Superconductors

Arulsamy

Ostrikov

2009

J Supercond Nov Magn

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The ionization energy theory is used to calculate the evolution of the resistivity and specific heat curves with respect to different doping elements in the recently discovered superconducting Pnictide materials. Electron-conduction mechanism in the Pnictides above the structural transition temperature is explained unambiguously, which is also consistent with other strongly correlated matter, such as cuprates, manganites, titanates and magnetic semiconductors.

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Magnetoresistivity model and ionization‐energy approximation for ferromagnets

Cited by 23 publications

References 39 publications

Reversible Carrier‐Type Transitions in Gas‐Sensing Oxides and Nanostructures

Reversible Carrier‐Type Transitions in Gas‐Sensing Oxides and Nanostructures

Diffusivity of adatoms on plasma-exposed surfaces determined from the ionization energy approximation and ionic polarizability

Electron-Conduction Mechanism and Specific Heat Above Transition Temperature in LaFeAsO and BaFe2As2 Superconductors

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