Does a nanoscale chromium film show superconductivity ?
Although previous studies have suggested that chromium films become superconductive (P. H. Schmidt et al., J. Appl. Phys., 44, 1833 (1973)), experimental evidence of this behavior, such as resistivity drop and the Meissner effect, is lacking. To clarify the relation between the electronic state and the thickness of chromium films, we precisely measured their electrical resistance. At low temperature, the resistivity-temperature curves of all films increased with decreasing temperature, deviating from those of bulk chromium. This suggests that two-dimensional conductivity influences the electrical resistance Although the resistance of several films changed discontinuously around 1.5 K, whether a superconducting transition occurs is inconclusive because a large residual electrical resistivity remained in all films. No anomaly in the resistance measurement was detected room temperature, and the discontinuous change in the resistance at low temperature may arise from suppression of antiferromagnetic interaction by thinning down the chromium element.