The polycrystalline layered compounds ${\mathrm{Fe}}_{0.25}{\mathrm{TiS}}_{2-y}{\mathrm{Se}}_y$ have been synthesized using the solid-state reaction method and characterized by means of x-ray diffraction, magnetization, electrical resistivity, and magnetoresistance measurements. The iron-chalcogen bonds in ${\mathrm{Fe}}_{0.25}{\mathrm{TiS}}_{2-y}{\mathrm{Se}}_y$ are found to be noticeably longer than the titanium-chalcogen bonds, and the bond lengths increase when sulfur is replaced by selenium, although the axial ratio $c/a$ remains unchanged. Although all compounds exhibit antiferromagnetic (AFM) order below $T_N$, increasing the selenium content in ${\mathrm{Fe}}_{0.25}{\mathrm{TiS}}_{2-y}{\mathrm{Se}}_y$ changes the magnetization behavior from Ising type in selenium-poor compounds ($y<0.5$) to Heisenberg type at $y>0.5$. In compounds with mixed anionic layers, the AFM order presumably coexists with the cluster glass state. At low concentrations of selenium ($y<0.5$), the compounds exhibit irreversible field-induced phase transitions to a metastable ferromagnetic (FM) state, which are accompanied by significant remnant magnetoresistance. Reversal of magnetization in the FM state is accompanied by a large hysteresis $H_c$ (up to $\sim 50$ kOe at 2 K). In the ${\mathrm{Fe}}_{0.25}{\mathrm{TiSe}}_2$ compound ($y=2$) with Néel temperature $T_N\sim 43$ K, an anomalous electrical resistivity behavior was detected in the vicinity of 110 K, which is associated with a charge-density-wave-type transition, similar to that observed in nonintercalated ${\mathrm{TiSe}}_2$.

Close

PrevNext

View figure in article

• Charge density waves
• Chemical bonding
• Magnetic order
• Magnetism
• Phase transitions
• Structural properties