Historical electronic components used in computers
Are you maybe thinking about magnetic logic?
Possibly the magnetic amplifier?

Related:


Brian Benchoff. "Making logic with inductors".
Edward P. Stabler. "Square-Loop Magnetic Logic Circuits".
Xichao Zhang, Motohiko Ezawa  &amp; Yan Zhou. "Magnetic skyrmion logic gates".
Longchen Liu. "Magnetic Logic Gate Using Ferromagnetic Hexagonal Nanodots".
Sergey Vasilyev, Marcos Pita, and Evgeny Katz. "Logic Gates Based on Magnetic Nanoparticles Functionalized with a Bioelectrocatalytic System".