1,964 research outputs found
Electrical Resistance Tomography of Conductive Thin Films
The Electrical Resistance Tomography (ERT) technique is applied to the
measurement of sheet conductance maps of both uniform and patterned conductive
thin films. Images of the sheet conductance spatial distribution, and local
conductivity values are obtained. Test samples are tin oxide films on glass
substrates, with electrical contacts on the sample boundary, some samples are
deliberately patterned in order to induce null conductivity zones of known
geometry while others contain higher conductivity inclusions. Four-terminal
resistance measurements among the contacts are performed with a scanning setup.
The ERT reconstruction is performed by a numerical algorithm based on the total
variation regularization and the L-curve method. ERT correctly images the sheet
conductance spatial distribution of the samples. The reconstructed conductance
values are in good quantitative agreement with independent measurements
performed with the van der Pauw and the four-point probe methods.Comment: IEEE Transactions on Instrumentation and Measuremen
Magnetoelectric properties of magnetite thin films
Resistivity, DC Hall effect and transverse magnetoresistance measurements were made on polycrystalline thin films of magnetite (Fe3O4) from 104K to room temperature. The Verwey transition is observed at TV=123K, about 4K higher than reported for bulk magnetite. The ordinary and extraordinary Hall coefficients are negative over the entire temperature range, consistent with negatively charged carriers. The extraordinary Hall coefficient exhibits a rho 1/3 dependence on the resistivity above TV and a rho 2/3 dependence below TV. The magnetoresistance is negative at all temperatures and for all magnetic field strengths. The planar Hall effect signal was below the sensitivity of the present experiment
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