A chiral fermionic valve driven by quantum geometry
Nature••business
Key Points:
- Devices were fabricated from PdGa crystals using Ga-ion focused-ion beam milling, polished to 1-4 μm thickness, and microstructured into three-arm geometries with Ti–Au electrical contacts; surface damage was minimized by careful processing and low-energy Ar ion etching.
- Electrical measurements were conducted at millikelvin temperatures and up to 2 T magnetic fields using lock-in amplifiers, revealing nonlinear Hall (NLH) responses dependent on device geometry, crystal orientation, and contact configuration, with enhanced third-order voltage signals when contacts connected to the top surface.
- The chiral fermionic valve states were defined by the relative magnitudes of chiral currents from topological Fermi pockets at Γ and R points, showing controllable valve positions
