Solid State Physics

Chapter 13

Superconductivity

13.1 SUPERCONDUCTIVITY

Resistivities (ρ) of metals show temperature dependence. This dependence is of a different nature in different temperature regions. In the room temperature region ρ ∝ T, in the intermediate temperature region ρ ∝ T³, in the low-temperature region ρ ∝ T⁵ and at still lower temperatures, ρ becomes independent of temperature or becomes a constant. This constant resistivity is called the residual resistivity and is attributed to the impurities or defects in the crystal. This was the state of information when temperature below 77 K (liquid nitrogen) was not achievable. In 1908, Kamerlingh Onnes for the first time liquefied helium and opened the way to perform experiments up to the temperature of ...