A breakthrough material that seemed to have impossible physical properties was actually just full of chemical dirt.
AgCrSe2 was hailed in the physics community for its extraordinary ability to move heat and electricity. This new study found that those unique effects were not actually part of the material's physics. Instead, they were artifacts caused by tiny chemical impurities left over from the growth process. When the crystals are grown perfectly, those special properties completely disappear. It serves as a stark reminder that what looks like a new law of nature is sometimes just a messy experiment.
Resolving growth-induced off-stoichiometry in AgCrSe$_2$ single crystals
arXiv · 2604.26887
The layered delafossite-like antiferromagnet AgCrSe$_2$ is a superionic conductor at high temperatures and has been reported to exhibit anomalous Hall behavior and Kondo physics at low temperatures. These extraordinary transport properties have been established almost exclusively on single crystals grown by chemical vapor transport, raising questions about the role of growth-induced off-stoichiometry. Using elemental analysis, single-crystal X-ray diffraction, and magnetization measurements, we