One of the best strategies for achieving faster computers is to mitigate the millisecond-order time delays arising from the transfer and storage of information between silicon-and magnetic-based memories. Segregating-binaryalloy (SBA)-type phase-change materials (PCMs), such as gallium antimonide-based systems, can store information on 10 ns time scales by using a single memory structure; however, these materials are hindered by the high consumption of energies and undergo elemental segregation around 620 K. Nanowire-like PCMs can achieve low-energy consumption but are often synthesized by vapor−liquid−solid methods above 720 K, which would cause irreversible corruption of SBA-based PCMs. Here we control the morphology, composition, and functionality of SBA-type germanium− tin oxide systems using template-driven nucleation that leverages the electrostatic-binding specificity of the M13 bacteriophage surface. A wirelike PCM was achieved, with controllable and reliable phase-changing signatures, capable of tens of nanoseconds switching times. This approach addresses some of the critical material compositional and structural constraints that currently diminish the utility of PCMs in universal memory systems.