Asad Niazi

Superparamagnetic-like ac susceptibility behavior in the partially disordered antiferromagnetic compound Ca 3 CoRhO 6

We report the results of dc and ac magnetization measurements as a function of temperature (1.8 - 300 K) for the spin-chain compound,

Low-temperature resistance minimum in non-superconducting 3R-Nb1+xS2 and 3R-GaxNbS2

{\mathrm{Ca}}_{3}{\mathrm{CoRhO}}_{6},

Magnetic anomalies in the spin-chain system Sr 3 Cu 1 − x Zn x IrO 6

which has been recently reported to exhibit a partially disordered antiferromagnetic (PDAF) structure in the range 30\char21{}90 K and spin-glass freezing below 30 K. We observe an unexpectedly large frequency dependence of ac susceptibility in the T range 30\char21{}90 K, typical of superparamagnets. In addition, we find that there is no difference in the isothermal remanent magnetization behavior for the two regimes below 90 K. These findings call for more investigations to understand the magnetism of this compound.

Magnetic anomalies in the spin-chain system Sr3Cu1-xZnxIrO6

We report the structural and electron transport properties of 3R-Nb1+xS2 (x≥0.07) and 3R-GaxNbS2 (0.1≤x≤0.33) prepared as polycrystalline pellets as well as single crystals grown by vapour transport. We observe a resistance minimum in these compounds between 20 and 60 K, with Tmin proportional to x. The resistance scales as ρ/ρmin(T/Tmin) in the range 0.2<T/Tmin<2 for different phases with x≤0.25 whose resistivity differs by an order of magnitude. Powder x-ray diffraction also shows progressively increasing intensity of superlattice lines with cation concentration. The thermopower changes sign around the resistance minimum. The explanation of the resistance minimum and the simultaneous rapid suppression of superconductivity is sought in electron-electron scattering effects in the presence of cation disorder in these narrow-band anisotropic materials.

Magnetic characteristics of Sr3Cu1−xZnxIrO6, a spin-chain system with competing interactions

We report the results of ac and dc magnetization (M) and heat-capacity (C) measurements on the solid solution, Sr

Magnetic anomalies in the spin chain system, Sr

_3

_3

Cu

Cu

_{1-x}

_{1-x}

Zn

Zn

_x