Researchers have developed a novel method for separating electrons based on their chirality, a property related to their spin, without the need for magnetic fields. The findings, published in the journal Nature, detail how scientists utilized the quantum geometry of topological bands in a material called palladium gallium (PdGa) to filter fermions, a type of particle that includes electrons, into distinct states polarized by their Chern number, a topological quantity.

This breakthrough allows for the spatial separation of currents with opposite fermionic chiralities, a feat demonstrated through the observation of their quantum interference. The team fabricated devices from single-crystal PdGa in a three-arm geometry, observing that the quantum geometry induced anomalous velocities in chiral fermions, leading to a nonlinear Hall effect.

"The resultant transverse chiral currents, possessing opposite anomalous velocities, are thereby spatially separated into the outer arms of the device," the study authors wrote. These chiral currents, existing in opposing Chern number states, also carry orbital magnetizations with opposite signs.

Traditional methods for manipulating chiral fermionic transport in topological systems often rely on strong magnetic fields or magnetic dopants. These are used to suppress unwanted transport and create an imbalance in the occupancy of states with opposite Chern numbers. The new method bypasses these requirements by exploiting the intrinsic quantum geometry of the material.

The research team believes this discovery could lead to the development of new electronic and spintronic devices. These devices could potentially offer more efficient and controllable ways to manipulate electron flow for advanced computing and data storage applications. Further research is underway to explore the full potential of this quantum-geometry-driven chiral fermionic valve and its applicability to other materials.