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arXiv · 1902.10856

A molecular diamond lattice antiferromagnet as a Dirac semimetal candidate

Yasuhiro Shimizu·Akihiro Otsuka·Mitsuhiko Maesato·Masahisa Tsuchiizu·Akiko Nakao·Hideki Yamochi·Takaaki Hiramatsu·Yukihiro Yoshida·Gunzi Saito
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Abstract

The ground state of a molecular diamond-lattice compound (ET)Ag$_4$(CN)$_5$ is investigated by the magnetization and nuclear magnetic resonance spectroscopy. We found that the system exhibits antiferromagnetic long-range ordering with weak ferromagnetism at a high temperature of 102 K owing to the strong electron correlation. The spin susceptibility is well fitted into the diamond-lattice Heisenberg model with a nearest neighbor exchange coupling of 230 K, indicating the less frustrated interactions. The transition temperature elevates up to $\sim$195 K by applying pressure of 2 GPa, which records the highest temperature among organic molecular magnets. The first-principles band calculation suggests that the system is accessible to a three-dimensional topological semimetal with nodal Dirac lines, which has been extensively searched for a half-filling diamond lattice.

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Yasuhiro Shimizu, Akihiro Otsuka, Mitsuhiko Maesato, Masahisa Tsuchiizu, Akiko Nakao, Hideki Yamochi, Takaaki Hiramatsu, Yukihiro Yoshida, Gunzi Saito. 2019-02-28. A molecular diamond lattice antiferromagnet as a Dirac semimetal candidate. https://doi.org/10.1103/physrevb.99.174417

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