Author

# T. B. Bhattacharya

Bio: T. B. Bhattacharya is an academic researcher. The author has contributed to research in topics: Magnetoresistance & Hall effect. The author has an hindex of 1, co-authored 1 publications receiving 11 citations.

Topics: Magnetoresistance, Hall effect, Mean free path, Thin film, Alloy

##### Papers

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TL;DR: In this article, an effective relaxation time is deduced from the variation of the Hall coefficient with the concentration which is found to be proportional to the mean free path of the electrons.

Abstract: Measurements on Hall constant and magnetoresistance of thin films (350 A-800 A) of Ag-Au alloys with concentrations up to 20% gold have been made. An effective relaxation time is deduced from the variation of the Hall coefficient with the concentration which is found to be proportional to the mean free path of the electrons. The mean free path of the film decreases by about a factor of 3 from the bulk value for silver on the addition of gold to silver. The results are consistent with those of other workers who have used different methods and also indicate that the relaxation time is anisotropic in thin films of alloy. Size effects have also been discussed.

12 citations

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TL;DR: It was found that topologically disordered 3D nanoporosity leads to extremely low magnetoresistance and anomalous temperature dependence as the characteristic length of nanoporous gold is tuned to be approximately 14 nm.

Abstract: We report the electric conductivity of three-dimensional (3D) nanoporous gold at low temperatures and in strong magnetic fields. It was found that topologically disordered 3D nanoporosity leads to extremely low magnetoresistance and anomalous temperature dependence as the characteristic length of nanoporous gold is tuned to be approximately 14 nm. This study underscores the importance of 3D topology of a nanostructure on electronic transport properties and has implications in manipulating electron transport by tailoring 3D nanostructures.

77 citations

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TL;DR: In this paper, the Boltzmann transport equation was used to define an effective relaxation time for thin metallic films subjected to a transverse magnetic field, and analytical expressions were derived for the Hall coefficient and conductivity in the case of nearly specular scattering on external surfaces.

Abstract: Defining an effective relaxation time and then using the Boltzmann transport equation, analytical expressions have been derived, in the case of nearly specular scattering on external surfaces (p>or=0.5), for the Hall coefficient and conductivity in thin metallic films subjected to a transverse magnetic field. The results for moderately high magnetic field agree well with previous theoretical works; at low magnetic field the Hall coefficient in thin films is greater than the bulk value RH0 and becomes identical with RH0 in strong magnetic field. The theoretical predictions agree well with experimental data on copper and potassium thin films.

21 citations

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TL;DR: In this article, a three-dimensional grain boundary model is used to calculate the transport properties of fine-grained films where background and grain boundaries scattering processes occur simultaneously, and analytical expressions are easily derived for the Hall coefficient and conductivity in polycrystalline films subjected to a transverse magnetic field.

Abstract: A three-dimensional grain boundary model can be used to calculate the transport properties of fine-grained films where background and grain boundaries scattering processes occur simultaneously. In the absence of a magnetic field a total relaxation time which is related to the grain size D and to the transmission coefficient t of electrons through grain boundaries is defined. Using the Boltzmann transport equation analytical expressions are easily derived for the Hall coefficient and conductivity in polycrystalline films subjected to a transverse magnetic field. The Hall coefficient is independent of both the grain parameters and the strength of the magnetic field whereas the film resistivity depends markedly on the grain size D and the transmission coefficient t. Some experimental data on polycrystalline films can be interpreted on the basis of these theoretical predictions.

13 citations

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TL;DR: In this paper, the authors derived analytical equations for the conductivity and the Hall coefficient of thin metallic films subjected to a longitudinal electric field and a transverse magnetic field from previously proposed general expressions.

Abstract: New analytical equations for the conductivity and the Hall coefficient of thin metallic films subjected to a longitudinal electric field and a transverse magnetic field are derived from previously proposed general expressions. Effects of electronic scattering at external surfaces and due to the magnetic field can be expressed separately. Conclusions are derived about the slight size effect in the Hall coefficient and its temperature dependence, which agree with previous experiments. A correlation between the size effects in the Hall coefficient and the product of the resistivity and the temperature coefficient of resistivity is proposed.

13 citations

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TL;DR: The transverse Hall coefficient of thin monocrystalline films was derived from the recently presented bidimensional conduction model by introducing a term in the Boltzmann equation representing the effective mean free path as discussed by the authors.

Abstract: The transverse Hall coefficient of thin monocrystalline filmsRHF is derived from the recently presented bidimensional conduction model by introducing a term in the Boltzmann equation representing the effective mean free path. Numerical evaluations ofRHF show that the size effect inRHF is less marked than that in resistivity and is much more sensitive to grain-boundary scattering than it is to external-surface scattering. Good agreement with the results from the previous experiments of several authors is found.

12 citations