Researchers have developed a novel method for separating electrons based on their chirality, a property related to their spin direction, using the quantum geometry of topological bands in a non-magnetic material. This breakthrough, detailed in a recent Nature publication, allows for the spatial separation of currents with opposite fermionic chiralities and their subsequent quantum interference, all without the need for magnetic fields or magnetic dopants, which are typically required for such manipulations.

The research team, whose members are affiliated with multiple institutions, demonstrated this phenomenon using devices fabricated from single-crystal PdGa, shaped in a three-arm geometry. The unique design leverages the quantum-geometry-induced anomalous velocities of chiral fermions, leading to a nonlinear Hall effect. This effect causes transverse chiral currents with opposing anomalous velocities to separate spatially into the outer arms of the device.

"This is a completely new way to control electron flow," said [Lead Researcher Name], a [Researcher Title] at [University/Institution]. "By using the inherent quantum properties of the material, we can manipulate electrons in ways that were previously only possible with strong magnetic fields."

The significance of this discovery lies in its potential to revolutionize electronic and spintronic devices. Current methods for manipulating chiral fermions often rely on high magnetic fields, which are energy-intensive and can limit the miniaturization of devices. The new method offers a more efficient and scalable alternative.

Topological semimetals, the class of materials used in this research, host fermions with opposite chiralities at topological band crossings. These materials have garnered significant attention in recent years due to their unique electronic properties. The team's innovation lies in their ability to exploit the quantum geometry of these materials to filter fermions by chirality into distinct Chern-number-polarized states. Chern number is a topological invariant that characterizes the electronic band structure.

The spatially separated chiral currents also carry orbital magnetizations with opposite signs, adding another layer of control and potential applications. The team observed the mesoscopic phase coherence of these chiral currents, further confirming the effectiveness of their method.

"The ability to separate and control chiral currents without magnetic fields opens up exciting possibilities for new types of electronic devices," explained [Co-author Name], a [Co-author Title] at [University/Institution]. "We envision applications in areas such as quantum computing, spintronics, and sensors."

The researchers are currently working on optimizing the device design and exploring other materials with similar quantum geometric properties. They believe that this approach can be extended to other topological materials, paving the way for a new generation of electronic devices based on quantum geometry. The next steps involve further investigation into the material properties and device optimization to enhance performance and explore potential applications.