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1

Transport characteristics of focused beam deposited nanostructures

100%

Ballestar A., Esquinazi P.

Nanofabrication

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2015

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vol. 2

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issue 1

EN

We review the transport properties of different nanostructures produced by ion- and electron-beam deposition, as prepared as well as after certain treatments. In general, the available literature indicates that the transport properties are determined by conduction processes typical for disordered metallic grains embedded in a carbon-rich matrix, including intergrain tunneling and variable range hopping mechanisms. Special emphasis is given to the superconducting behavior found in certain Tungsten-Carbide nanostructures that, in a certain field and temperature range, is compatible with that of granular superconductivity. This granular superconductivity leads to phenomena like magnetic field oscillations as well as anomalous hysteresis loops in the magnetoresistance.

2

Investigations of Structural, Elastic, Electronic, Magnetic and Transport Properties of the Heusler Compounds Zr₂PdZ (Z = Al, Ga, and In): FP-LAPW Method

88%

Khelfaoui F., Boudali A., Bentayeb A., El Hachemi Omari L., Si Abderrahmane Y.

Acta Physica Polonica A

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2018

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vol. 133

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issue 1

157-163

EN

Structural, elastic, electronic, magnetic and thermoelectric properties of the Heusler compounds: Zr₂PdAl, Zr₂PdGa, and Zr₂PdIn are performed using generalized gradient approximation with exchange-correlation function of the Perdew-Burke-Ernzerhof. The elastic constants are calculated at P=0 GPa. From the obtained elastic parameters, it is inferred that these compounds, with the Hg₂TiCu-type structure, are elastically stable and ductile in nature. The calculated density of states, magnetic moments and band structure are also given. The band structures of these compounds reveal that all of them have almost half metallic character with the narrow indirect band gap in the minority spin channel that amounts to 0.36, 0.46, and 0.40 eV for Zr₂PdAl, Zr₂PdGa, and Zr₂PdIn, respectively. The total spin magnetic moments (M_{tot}) of the considered compounds are very close to integer value 3, which satisfies a Slater-Pauling type rule for localized magnetic moment systems M_{tot}=Z_{T}-18, where Z_{T}=21 is the number of valence electrons in the primitive cell. The thermoelectric properties of these materials are discussed on the basis of the Seebeck coefficients, electrical and thermal conductivity relative to relaxation time as a function of temperature, at the Fermi level, using the Boltzmann transport theory. After several browse in the literature, the obtained results are the first predictions of the physical properties for the inverse full-Heusler compounds Zr₂PdZ (Z = Al, Ga and In).

3

Magnetic and transport properties of monocrystallineFe 3 O 4

63%

Paul K.

Open Physics

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2005

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vol. 3

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issue 1

115-126

EN

A monocrystal ofFe 3 O 4 is characterized by resistance, magnetoresistance and magnetic measurements in a temperature range from 4.2 K to 350 K and magnetic field-cycling from −9 T to 9 T. The resistance measurements revealed a metal-insulator Verwey transition (VT) atT v=123.76 K with activation energy E=92.5 meV at T >T v and temperature-substitute for the activation energy below the VT,T 0=E/k B≈3800 K within 70 K–110K. The magnetotransport results independently verified the VT at 123.70 K, with discontinuous change in the magnetic moment ΔM≈0.21 ΔM≈0.21μ B and resistance hysteresis, dependent on the magnetic field in a narrow temperature range of 0.4° around theT v. The magnetic characterization established self consistentlyT v as ≈123.67 K, the jump in the magnetization at the VT≈0.25μ B and confirmed, that the magnetocrystalline anisotropy is the main microscopic mechanism responsible for the magnetization of the monocrystal (88%) with additional natural and imposed defects contributing as 12%.

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1 Acta Physica Polonica A

1 Nanofabrication

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1 El Hachemi Omari L.

1 Esquinazi P.

1 Khelfaoui F.

1 Paul K.

1 Si Abderrahmane Y.

Transport characteristics of focused beam deposited nanostructures

Investigations of Structural, Elastic, Electronic, Magnetic and Transport Properties of the Heusler Compounds Zr₂PdZ (Z = Al, Ga, and In): FP-LAPW Method

Magnetic and transport properties of monocrystallineFe 3 O 4