Magnetism and electronic dynamics in $CuC{r}_{2-x}S{n}_x{S}_4$ spinels studied by transferred hyperfine fields at ${}^{119}Sn$ and muon spin rotation and relaxation

Abstract

We investigated magnetization, muon spin rotation ($\mu$SR), and ${}^{119}Sn$ Mössbauer spectroscopy on Sn substituted $CuC{r}_{2-x}S{n}_x{S}_4$ (x=0.03 and 0.08) spinel compounds. The magnetization and $\mu$SR results reveal similar additional low-temperature magnetic transitions around 80 K and 40 K as found for the undoped material, indicating a magnetic ground state deviating from a simple collinear ferromagnet. The observed changes in the Mössbauer hyperfine spectra are less pronounced and are discussed in view of the different positions of the local probes ${\mu }^{+}$ and ${}^{119}Sn$ and their different magnetic coupling to the magnetic Cr lattice. Above 80 K, both $\mu$SR and Mössbauer spectra show temperature-dependent inhomogeneous broadening either due to structural or charge disorder and changing spin dynamics that can be related to a precursor magnetic phase above the well-defined static low-temperature phase.

17 pages, 13 figures