Scrypt is Maximally Memory-Hard.
Joël Alwen, Binyi Chen, Krzysztof Pietrzak, Leonid Reyzin, Stefano Tessaro · IACR Cryptology ePrint Archive · 2016
Memory-hard functions (MHFs) are hash algorithms whose evaluation cost is dominated by memory cost. As memory, unlike computation, costs about the same across different platforms, MHFs cannot be evaluated at significantly lower cost on dedicated hardware like ASICs. MHFs have found widespread applications including password hashing, key derivation, and proofs-of-work.