Pulsed Fields Unlock Hidden Electron Behavior in the Magnetic Material Fe₃₋ₓGeTe₂

What is the finding

Scientists studied a magnetic material called Fe₃₋ₓGeTe₂ (FGT) under very strong magnetic fields up to 60 T at different temperatures. They observed a small but important change in its behavior at 80 K (about -193°C), seen as a shift in how its magnetization and electrical resistivity responded to the magnetic field. This subtle change signals a significant rearrangement in how the material’s electrons behave, caused by a phenomenon known as the Kondo effect, which affects how electrons interact with magnetic impurities.

Why is this important?

FGT is a special material that grows in thin layers, making it ideal for building devices. It has excellent electrical conductivity, unusual magnetic properties that work at high temperatures, and a strong connection between its magnetism and conductivity. These features make FGT a promising candidate for low-power spintronic devices, which use the spin of electrons, not just their charge, for more efficient data storage and transfer. This study highlights the need to consider the Kondo effect—a rare electron behavior—when designing FGT-based devices. What’s exciting is that the Kondo effect, usually seen in rare elements like Uranium or Cerium, appears in FGT, a material made from common iron, opening up new possibilities for advanced technologies.

Who did the research?

S. Vaidya¹, M. J. Coak ^1,2, D. A. Mayoh¹, M. R. Lees¹, G. Balakrishnan¹, J. Singleton³ and P. A. Goddard¹

¹Department of Physics, University of Warwick, ²School of Physics & Astronomy, University of Birmingham, ³National MagLab - LANL

Why did they need the MagLab?

To detect the Kondo effect, researchers needed to measure resistivity and magnetization of FGT at magnetic fields above 50 T. During some measurements, FGT crystals were rotated to precise angles in the field at temperatures down to 0.5 K. This combination of extreme conditions is not accessible in ordinary laboratories, and can be found and used at the MagLab’s Pulsed-Field Facility.

Details for scientists

• View or download the expert-level Science Highlight, Pulsed fields detect a dramatic change of electronic character in the ferromagnet Fe_3−xGeTe₂
• Read the full-length publication, Direct evidence from high-field magnetotransport for a dramatic change of quasiparticle character in van der Waals ferromagnet Fe_3-xGeTe₂, in Physical Review Research

Funding

This research was funded by the following grants: K. M. Amm (NSF DMR-2128556); J. Singleton (NSF DMR-2128556; DOE Science of 100 T); Goddard/Balakrishnan (ERC 681260, EPSRC EP/T005963/1, EP/N032128/1)

For more information, contact Neil Harrison.