Some cuprates have an upper critical field of about 100 tesla. However, cuprate materials are brittle ceramics which are expensive to manufacture and not easily turned into wires or other useful shapes. Also, high-temperature superconductors do not form large, continuous superconducting domains, but only clusters of microdomains within which superconducting occurs. They are therefore unsuitable for applications requiring actual superconducted currents, such as magnets for magnetic resonance spectrometers.
IOW, we don’t have a high temperature superconducting material that’s suitable for use in an MRI scanner yet.
That's still just cuprate superconductors except flattened inside of a metal tube. It's still expensive, inflexible, and for reasons to do with the SC physics, behave differently than the kind of Type 1 superconductors needed for MRIs and NMRs (high temperature superconductors are Type 2 and are a drastically different phenomenon).
Some cuprates have an upper critical field of about 100 tesla. However, cuprate materials are brittle ceramics which are expensive to manufacture and not easily turned into wires or other useful shapes. Also, high-temperature superconductors do not form large, continuous superconducting domains, but only clusters of microdomains within which superconducting occurs. They are therefore unsuitable for applications requiring actual superconducted currents, such as magnets for magnetic resonance spectrometers.
IOW, we don’t have a high temperature superconducting material that’s suitable for use in an MRI scanner yet.