The cryotron is a switch that operates using superconductivity. The cryotron works on the principle that magnetic fields destroy superconductivity. This simple device consists of two superconducting wires (e.g. tantalum and niobium) with different critical temperature (Tc). A small size relay or switch made of superconductors. They consume very less current. Let the critical field of the material A be HCA and that of B be HCB and also HCA < HCB . If a current I is passed through the material B, the current induces a magnetic field H. If this induced field H happens to be greater than HCA then the superconducting property of the material A gets destroyed. Hence the resistivity increases and the contact is broken. Thus, the current in A can be controlled by the current in B and hence this system can act as a relay or switch element.
