A detailed study of the electronic transport and magnetic properties of Fe1−xCuxCr2S4 (x≤0.5) on single crystals is presented. The resistivity is investigated for 2≤T≤300 K in magnetic fields up to 14 Tesla and under hydrostatic pressure up to 16 kbar. In addition magnetization and ferromagnetic resonance (FMR) measurements were performed. FMR and magnetization data reveal a pronounced magnetic anisotropy, which develops below the Curie temperature, TC, and increases strongly towards lower temperatures. Increasing the Cu concentration reduces this effect. At temperatures below 35 K the magnetoresistance, MR=ρ(0)ρ(0)−ρ(H), exhibits a strong dependence on the direction of the magnetic field, probably due to an enhanced anisotropy. Applying the field along the hard axis leads to a change of sign and a strong increase of the absolute value of the magnetoresistance. On the other hand the magnetoresistance remains positive down to lower temperatures, exhibiting a smeared out maximum with the magnetic field applied along the easy axis. The results are discussed in the ionic picture using a triple-exchange model for electron hopping as well as a half-metal utilizing a band picture.
@article{arxiv.cond-mat/0210134,
title = {Anisotropic Colossal Magnetoresistance Effects in Fe_{1-x}Cu_xCr_2S_4},
author = {V. Fritsch and J. Deisenhofer and R. Fichtl and J. Hemberger and H. -A. Krug von Nidda and M. Muecksch and M. Nicklas and D. Samusi and J. D. Thompson and R. Tidecks and V. Tsurkan and A. Loidl},
journal= {arXiv preprint arXiv:cond-mat/0210134},
year = {2009}
}