A superconductor tape stack, comprising a first superconductor tape and a second superconductor tape, wherein each of the first superconductor tape and the second superconductor tape includes a substrate and a superconductor film adjacent to the substrate, the first superconductor tape and the second superconductor tape are arranged in a face-to-back configuration within the superconductor tape stack, and the substrate of the first superconductor tape, the second superconductor tape, or each of the first superconductor tape and the second superconductor tape has a resistivity of at most 50 μΩcm.