Quantum Oscillations and Magnetic Reconstruction in the Delafossite PdCrO${}_2$

Abstract

We report quantum oscillation data on the metallic triangular antiferromagnet PdCrO${}_2$. We find that, to very high accuracy, the observed frequencies of PdCrO${}_2$ can be reproduced by reconstruction of the (nonmagnetic) PdCoO${}_2$ Fermi surface into a reduced zone. The reduced zone corresponds to a magnetic cell containing six chromium sites, giving a $\sqrt{3}\times \sqrt{3}$ in-plane reconstruction, and $\times 2$ interplane reconstruction. The interplane ordering represents a reduction in lattice symmetry, possibly to monoclinic, and an associated lattice distortion is expected. In addition, we report a magnetic transition under an applied in-plane field that is probably equivalent to the spin-flop transition reported for CuCrO${}_2$, and present data on its field-angle dependence. We also report measurements of the resistivity of PdCrO${}_2$ up to 500 K.

9 pages, 10 figures