Non-van der Waals honeycomb antiferromagnet SrRu$_2$O$_6$ down to a few layers

Suvidyakumar Homkar; Bharat Chand; Shatruhan Singh Rajput; Sandeep Gorantla; Tilak Das; Rohit Babar; Shivprasad Patil; Ruediger Klingeler; Sunil Nair; Mukul Kabir; Ashna Bajpai

arXiv · 1904.12326

Non-van der Waals honeycomb antiferromagnet SrRu$_2$O$_6$ down to a few layers

Suvidyakumar Homkar·Bharat Chand·Shatruhan Singh Rajput·Sandeep Gorantla·Tilak Das·Rohit Babar·Shivprasad Patil·Ruediger Klingeler·Sunil Nair·Mukul Kabir·Ashna Bajpai

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Abstract

The current family of experimentally realized two-dimensional magnetic materials consist of 3$d$ transition metals with very weak spin-orbit coupling. In contrast, we report a new platform in a chemically bonded and layered 4$d$ oxide, with strong electron correlations and competing spin-orbit coupling. We synthesize ultra-thin sheets of SrRu$_2$O$_6$ using scalable liquid exfoliation. These exfoliated sheets are characterized by complementary experimental and theoretical techniques. The thickness of the nano-sheets varies between three to five monolayers, and within the first-principles calculations, we show that antiferromagnetism survives in these ultra-thin layers. Experimental data suggest that exfoliation occurs from the planes perpendicular to the $c$-axis as the intervening hexagonal Sr-lattice separates the two-dimensional magnetic honeycomb Ru-layers. The high-resolution transmission electron microscope images indicate that the average inter-atomic spacing between the Ru-layers is slightly reduced, which agrees with the present calculations. The signatures of rotational stacking of the nanosheets are also observed. Such new two-dimensional platform offers enormous possibilities to explore emergent properties that appear due to the interplay between magnetism, strong correlations and spin-orbit coupling. Moreover, these effects can be further tuned as a function of layer thickness.

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Suvidyakumar Homkar, Bharat Chand, Shatruhan Singh Rajput, Sandeep Gorantla, Tilak Das, Rohit Babar, Shivprasad Patil, Ruediger Klingeler, Sunil Nair, Mukul Kabir, Ashna Bajpai. 2019-04-28. Non-van der Waals honeycomb antiferromagnet SrRu$_2$O$_6$ down to a few layers. https://arxiv.org/abs/1904.12326

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