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A direct method to calculate the activation energy from the resistance transition is proposed for high temperature superconductors (HTSCs). It is applied to Er-doped melted textured growth (MTG) YBa2Cu3O7−δ (YBCO) crystals. The activation energy is found to be U(T, H) = (Tp−T)m(H/H0)−β, with m = 2.1 ± 0.2 and β = 0.97. All the low temperature data are scaled onto a straight line by the plot of lnR/Rn versus , which supports the proposed method.

Both lateral photovoltage (LPV) and positive magnetoresistance (MR) are observed in Co/Mn/Co/c-Si structure. The LPV shows a large sensitivity of 10 mV mm−1 as a laser spot is moved on a film surface. An apparent positive MR of 2.8% (at 4.2 K) is also found in the structure and is explained based on the enhanced scattering at the interface. The LPV is discussed in terms of the metal–semiconductor junction that exists between the film and the Si substrate. The combined properties add functionality to the single magnetic or optic property and facilitate matters for dual role devices that are both sensitive to the light and magnetic field.