Restoring symmetry in antiferromagnets links Weyl points into lines that create massless particle cones.

Electrons in solid materials can act like exotic particles that travel without mass. Scientists recently discovered Heesch Weyl materials. These are special magnets where these particle points are permanently pinned in place, preventing opposite points from meeting and canceling out. In this study, researchers looked at what happens when these magnets have achiral symmetry, meaning their structure matches its own mirror reflection. They found that restoring mirror or rotoinversion symmetries connects these pinned points with long, two-fold touching paths called Heesch nodal lines. Slicing through these lines creates flat planes filled with massless electron cones. A large group of these magnets shows a nonlinear anomalous Hall effectanomalous Hall effectA voltage generated perpendicular to both current and magnetic field, even in materials with no net magnetism., a sideways electrical response, starting at the third order. Testing materials like MnTe, CrSb, and Mn3GaN confirmed these lines exist. Finally, stretching the crystals breaks the symmetry, opening energy gaps that could help create strong sideways electrical effects.

Why it matters

This work helps scientists predict and find materials with exotic electronic properties for future tech. Antiferromagnets, which are common in nature, can now be tuned to have effects like the anomalous Hall effect, key for magnetic sensors and memory devices.

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