Superconducting properties of commercially available solders for low-field applications

Solders with superconducting transitions around are useful in low magnetic field environments for AC current leads or in electrical and mechanical bonds. Accurate knowledge of these solders’ superconducting properties is needed for improving high precision experiments. We have measured the electrical resistance of five commercially-available eutectic or near-eutectic solders: 50 %Sn-50 %Pb, 60 %Sn-40 %Pb, 60 %Sn-40 %Pb-0.3 %Sb, 52 %In-48 %Sn, and 96.5 %Sn-3.5 %Ag, down to and in applied magnetic fields from 0 to 0.1 . We report critical temperatures , 90 %-to-10 % transition widths , and zero-temperature critical fields . Our best candidate for low-loss AC current wiring in low fields is 50 %Sn-50 %Pb, which has a zero-field (with ), and remained high at ( ). We also report, for the first time, and of 60 %Sn-40 %Pb-0.3 %Sb and of 96.5 %Sn-3.5 %Ag. Our ( ) for 96.5 %Sn-3.5 %Ag disagrees with a widely adopted value. • Superconducting transitions of five widely used solder wires at 0.1 T were measured. • Our values disagreed with existing for tin-lead and tin-silver solders. • Antimony-doped tin-lead solder properties are reported for the first time. • 50 % Tin - 50 % Lead solder identified as best wiring for low-loss AC current transport. • Transition widths are included to aid in the precise use of materials.