Topologically Nontrivial Phase-Change Compound GeSb<sub>2</sub>Te<sub>4</sub>
Munisa Nurmamat, Okamoto Kazuaki, Siyuan Zhu, Tatiana V. Menshchikova, I. P. Rusinov, Vladislav O. Korostelev, K. Miyamoto, Taichi Okuda, Takeo Miyashita, Xiaoxiao Wang, Y. Ishida, Kazuki Sumida, Eike F. Schwier, Mao Ye, Ziya S. Aliev, М. Б. Бабанлы, И. Р. Амирасланов, Е. В. Чулков, К. А. Кох, О. Е. Терещенко, K. Shimada, Shik Shin, A. Kimura
Abstract
Chalcogenide phase-change materials show strikingly contrasting optical and electrical properties, which has led to their extensive implementation in various memory devices. By performing spin-, time-, and angle-resolved photoemission spectroscopy combined with the first-principles calculation, we report the experimental results that the crystalline phase of GeSb2Te4 is topologically nontrivial in the vicinity of the Dirac semimetal phase. The resulting linearly dispersive bulk Dirac-like bands that cross the Fermi level and are thus responsible for conductivity in the stable crystalline phase of GeSb2Te4 can be viewed as a 3D analogue of graphene. Our finding provides us with the possibility of realizing inertia-free Dirac currents in phase-change materials.