Magnetic hyperfine field at Cr site in AgCrO$_2$ given by perturbed angular correlations

This work presents an electric field gradient and magnetic hyperfine field study, in the AgCrO$_2$ multiferroic with triangular spin lattice. The temperature dependence of the electric field gradient (EFG) and magnetic hyperfine field (MHF) at Cr site was studied at ISOLDE via perturbed angular correlation measurements with the $^{111}$In probe, at room temperature and below the Neel temperature (T=21 K) down to presence of two distinct local environments. One axial symmetric EFG with a very low MHF, and a non-axially symmetric EFG with a much higher one. The temperature dependences of MHF magnitude and of the angle between the MHF and the principle component of the EFG are investigated.