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arXiv · 1411.1946

Temperature evolution of magnetic and transport behavior in 5\textit{d} Mott insulator Sr$_2$IrO$_4$: Significance of magneto-structural coupling

Imtiaz Noor Bhatti·R. Rawat·A. Banerjee·A. K. Pramanik
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Abstract

We have investigated the temperature evolution of magnetism and its interrelation with structural parameters in perovskite-based layered compound Sr$_2$IrO$_4$, which is believed to be a $J_{eff}$ = 1/2 Mott insulator. The structural distortion plays an important role in this material which induces a weak ferromagnetism in otherwise antiferromagnetically ordered magnetic state with transition temperature around 240 K. Interestingly, at low temperature below around 100 K, a change in magnetic moment has been observed. Temperature dependent x-ray diffraction measurements show sudden changes in structural parameters around 100 K are responsible for this. Resistivity measurements show insulating behavior throughout the temperature range across the magnetic phase transition. The electronic transport can be described with Mott's two-dimensional variable range hopping (VRH) mechanism, however, three different temperature ranges are found for VRH, which is a result of varying localization length with temperature. A negative magnetoresistance (MR) has been observed at all temperatures in contrast to positive behavior generally observed in strongly spin-orbit coupled materials. The quadratic field dependence of MR implies a relevance of a quantum interference effect.

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Imtiaz Noor Bhatti, R. Rawat, A. Banerjee, A. K. Pramanik. 2014-11-07. Temperature evolution of magnetic and transport behavior in 5\textit{d} Mott insulator Sr$_2$IrO$_4$: Significance of magneto-structural coupling. https://doi.org/10.1088/0953-8984%2F27%2F1%2F016005

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