Electrical resistance and structural characteristics of chromium films produced by low-temperature condensation

A study was made of amorphous chromium films produced by condensation on a substrate at liquid-helium temperature and then heated to various temperatures (up to approximately 350 °K), namely the temperature dependence of their electrical resistance was measured and their structural characteristics were determined with the aid of electron diffraction. It has been found that the coordination structure of such amorphous films depends on their thickness and temperature. The dependence of the crystalline transition temperature on the thickness of amorphous chromium films has been established, and features of this transition are discussed. The reversible trend of the resistance R(T) for amorphous chromium films as well as for crystalline ones is characterized by a negative temperature coefficient of resistance. A comparison of experimental data with known theories reveals that the R(T) curves agree closely with the Ohkawa theory, which had been developed for metals with a very short mean free path for electrons. The irreversible decrease of the electrical resistance of chromium films in the 250−320 °K temperature range is also discussed. It is proposed that this decrease is associated with a phase transition of chromium from the antiferromagnetic to the paramagnetic state.

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