Ferromagnetism and structural transformations caused by Cr intercalation intoTiTe2

Abstract

Crystal structure investigations, electrical resistivity, and magnetic measurementshave been performed for polycrystalline samples of intercalated compoundsCrxTiTe2 with a Crconcentration up to x = 0.65. According to the room-temperature x-ray diffraction study ofCrxTiTe2, theinitial hexagonal crystal structure transforms to a monoclinic one with increasing Cr content up tox≥0.5 due to the ordering of Cr ions. The intercalation results in the change of the resistivity behavior inCrxTiTe2 from metal-like atx = 0 to insulator-likeabove x = 0.33 and leads to ferromagnetic ordering of Cr magnetic moments atx≥0.5. For thecompound Cr0.25TiTe2, structural transformations and anomalous resistivity behavior are observed around 230 K,which cannot be explained only by the order–disorder transition within the subsystem ofintercalated Cr ions. Structural changes within Te–Ti–Te sandwiches associated withcharge density wave instability are suggested to be involved in this phase transition as well.