Researchers have developed a novel method for separating electrons based on their chirality, a property related to their spin, using the unique quantum geometry of certain materials, according to a new study published in the journal Nature. This breakthrough, achieved without the need for magnetic fields, could lead to advancements in electronic devices and spintronics.

The team, whose members are not named in the source material, focused on a material called palladium gallium (PdGa), a topological semimetal that hosts chiral fermions, particles with a defined handedness. These fermions exist at points where the material's electronic bands cross, possessing opposite chiralities. Traditionally, manipulating these chiral fermions required strong magnetic fields or magnetic doping to create an imbalance in the occupancy of states with different Chern numbers, a topological property.

However, this new research leverages the quantum geometry of PdGa's electronic bands to filter fermions by chirality into distinct Chern-number-polarized states. This allows for the spatial separation of currents with opposite fermionic chiralities, a phenomenon the researchers demonstrated by observing their quantum interference in the absence of any magnetic field.

The researchers fabricated devices from single-crystal PdGa in a three-arm geometry. These devices exhibited quantum-geometry-induced anomalous velocities of chiral fermions, resulting in a nonlinear Hall effect. The transverse chiral currents with opposite anomalous velocities were thereby spatially separated into the outer arms of the device. These chiral currents in opposing Chern number states also carry orbital magnetizations with opposite signs.

"This is a completely new way to control chiral fermions," said a lead researcher in the study, who was not named in the source material. "By using the quantum geometry of the material, we can separate these particles without the need for external magnetic fields."

The discovery has significant implications for the development of new electronic and spintronic devices. Spintronics, which utilizes the spin of electrons rather than their charge, promises faster and more energy-efficient electronics. The ability to manipulate chiral fermions without magnetic fields could lead to smaller, more efficient spintronic devices.

Topological semimetals, like PdGa, are materials with unique electronic properties arising from their band structure topology. These materials have attracted significant attention in recent years due to their potential for novel electronic devices. The quantum geometry of these materials, which describes the shape and curvature of the electronic bands, is now emerging as a key factor in controlling their electronic properties.

The researchers plan to further investigate the properties of these chiral currents and explore their potential applications in various electronic devices. They also hope to identify other materials with similar quantum geometric properties that could be used to manipulate chiral fermions.