Absence of Antiferromagnetism in Ti2O3

Abstract

The possible existence of antiferromagnetism in Ti2O3 has important theoretical implications associated with the explanation of the metal-to-semiconductor transition in this material. A previous neutron-diffraction study, using unpolarized neutrons, indicated that Ti2O3 was antiferromagnetic with the α-Fe2O3 structure. More recently, contradictory findings were reported which eliminated the α-Fe2O3 structure but could not rule out the type of ordering found in Cr2O3. We have reexamined this substance, using the new technique of neutron-polarization analysis. With this technique, the coherent scattering can be separated into nuclear and magnetic parts at a fixed temperature. It is possible to detect small magnetic contributions, even when the magnetic and nuclear peaks have the same scattering vector. At room temperature, we find no evidence for either the α-Fe2O3 or the Cr2O3 magnetic structure.