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Anisotropic Colossal Magnetoresistance Effects in Fe_{1-x}Cu_xCr_2S_4

V. Fritsch·J. Deisenhofer·R. Fichtl·J. Hemberger·H. -A. Krug von Nidda·M. Muecksch·M. Nicklas·D. Samusi·J. D. Thompson·R. Tidecks·V. Tsurkan·A. Loidl
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Abstract

A detailed study of the electronic transport and magnetic properties of Fe$_{1-x}$Cu$_x$Cr$_2$S$_4$ ($x \leq 0.5$) on single crystals is presented. The resistivity is investigated for $2 \leq T \leq 300$ 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, $T_{\mathrm{C}}$, and increases strongly towards lower temperatures. Increasing the Cu concentration reduces this effect. At temperatures below 35 K the magnetoresistance, $MR = \frac{ρ(0) - ρ(H)}{ρ(0)}$, 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.

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V. Fritsch, J. Deisenhofer, R. Fichtl, J. Hemberger, H. -A. Krug von Nidda, M. Muecksch, M. Nicklas, D. Samusi, J. D. Thompson, R. Tidecks, V. Tsurkan, A. Loidl. 2003-04-30. Anisotropic Colossal Magnetoresistance Effects in Fe_{1-x}Cu_xCr_2S_4. https://doi.org/10.1103/physrevb.67.144419

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