Long-range magnetic order and spin-lattice coupling in delafossite ${\text{CuFeO}}_2$

The electronic and magnetic properties of the delafossite ${\text{CuFeO}}_2$ are investigated by means of electronic structure calculations. They are performed using density functional theory in the generalized gradient approximation, as well as the new full-potential augmented spherical wave method. The calculations reveal three different spin states at the iron sites. Using for the first time the experimentally determined low-temperature crystal structure, we find long-range antiferromagnetic ordering in agreement with experiment. In addition, our calculations show that nonlocal interactions as covered by the generalized gradient approximation lead to a semiconducting ground state.

Figure 1

(Color online) Partial densities of states (DOS) of rhombohedral ${\text{CuFeO}}_2$. Selection of $\text{Fe}3d$ orbitals in this and the subsequent figures is relative to the local rotated reference frame, see text.

Figure 2

(Color online) Partial densities of states (DOS) of rhombohedral ferromagnetic (a) low-spin, (b) intermediate-spin, and (c) high-spin ${\text{CuFeO}}_2$.

Figure 3

(Color online) Partial densities of states (DOS) of monoclinic antiferromagnetic high-spin ${\text{CuFeO}}_2$.