The resistivity as a function of temperature from 0.6 to 300 K for epitaxial and polycrystalline Cr thin films is presented and fit to a model which includes electron-phonon scattering and resonant impurity scattering. Resonant impurity scattering from localized defect states in the spin-density wave gap leads to very high residual resistivity (up to 400 μΩcm) and a minimum at low temperatures (below 100 K). This is strong experimental evidence for resonant impurity scattering due to defects in pure Cr rather than dopant atoms. The magnitude of the resistivity minimum scales linearly with the residual resistivity over 2 orders of magnitude. At moderate temperatures (100-300 K) the resistivity shows a positive, linear temperature dependence due to electron-phonon scattering. Defects affect the electron-phonon scattering as well leading to a variation in the effective Debye temperature and resistivity slope between samples, a significant deviation from Matthiessen's rule. © 2009 The American Physical Society.

A microfabricated amorphous silicon nitride membrane-based nanocalorimeter is proposed to be suitable for an x-ray transparent sample platform with low power heating and built-in temperature sensing. In this work, thermal characterization in both air and vacuum are analyzed experimentally and via simulation. Infrared microscopy and thermoreflectance microscopy are used for thermal imaging of the sample area in air. While a reasonably large isothermal area is found on the sample area, the temperature homogeneity of the entire sample area is low, limiting use of the device as a heater stage in air or other gases. A simulation model that includes conduction, as well as radiation and convection heat loss, is presented with radiation and convection parameters determined experimentally. Simulated temperature distributions show that the homogeneity can be improved by using a thicker thermal conduction layer or reducing the pressure of the gas in the environment but neither are good solutions for the proposed use. A new simple design that has improved temperature homogeneity and a larger isothermal area while maintaining a thin thermal conduction layer is proposed and fabricated. This new design enables applications in transmission x-ray microscopes and spectroscopy setups at atmospheric pressure.