Opus 5.5 agents discover two room-temperature magnetic semiconductor candidates

Vals AI published a blog post on October 4, 2026 reporting that AI agents running Claude Opus 5.5 (Anthropic) designed one and found another of two candidate materials that might sort electrons by spin at room temperature. The agents ran density functional theory calculations, which estimate a material's electronic structure from quantum mechanics. The target was a semiconductor with zero net spin moment whose up-spin and down-spin atoms sit in different surroundings, so electrons can be sorted by spin.

The candidates are YBaMnFeO5, a compound the agents designed, and potassium vanadium chromium cyanide, first reported in 1999. The post's caveats are central: the predictions assume a perfect, dry crystal, the designed compound may come out scrambled under standard synthesis, and two calculation methods disagree on whether water in the older material's pores preserves spin sorting. The only measured property is the 1999 sample's magnetic ordering temperature of 376 K, which is not a measurement of spin sorting. The post says neither the band gap nor the spin sorting has been measured, so these are candidates for lab work.