https://phys.org/news/2018-05-one-way-roads-currents.html

Researchers from Singapore University of Technology and Design (SUTD), University Insubria and Universidade Federal de Minas Gerais report a new approach to controlling spin currents based on strong spin-spin interactions, which results in diodes for spin current with a giant rectification. In this work, the researchers demonstrated analytically and via advanced numerical simulations that if the interactions are stronger than a certain magnitude, the system can drastically change and becomes an insulator, preventing currents from flowing. Interestingly, this drastic change to insulating behaviour only occurs when trying to impose the current in one direction. When trying to drive a spin current in the opposite direction, the flow is possible and the system is not an insulator.

These predictions could lead to substantial progress in material science, and new devices could be built based on this principle. The researchers propose experiments with atoms near absolute zero or with structures made of a few atoms deposited carefully on surfaces.