Effect of Cr deficiency on physical properties of triangular-lattice antiferromagnets CuCr1-xO2 (0 <= x <= 0.10)
Journal
Journal of Applied Physics
Journal Volume
109
Journal Issue
7
Pages
07D908
Date Issued
2011
Author(s)
Abstract
Structural, transport, and magnetoelectric (ME) properties of delafossite oxides CuCr1-xO2 with 0≦x≦0.10 were extensively investigated. The Rietveld refinement shows that the Cu-O bond length decreases with increasing Cr deficiency, indicative of the presence of a mixed valence state of Cu/Cu2 and an enhancement of the hybridization between Cu 3d and O 2p orbitals. As a result, it leads to a decrease of room-temperature resistivity by two orders of magnitude. The deduced effective moment for the Cr-deficient samples is larger than the one only taking into account the contribution from Cr3 with S 3/2. This demonstrates that Cu 2 is present in the Cr-deficient samples, giving rise to excess holes at the Cu site. Below TN(Cr) ∼ 24 K, the magnetocapacitance [ε(H)- ε (0)]/ε(0) exhibits a distinct field dependence and deviates from the square of magnetization M2. These findings suggest that the ME coupling in CuCr1-xO2 with higher x is modulated by an increase of the spin fluctuations in the CrO2 triangular lattice through the interplay between charge and spin degrees of freedom. © 2011 American Institute of Physics.
SDGs
Type
journal article