Pressure-induced coherent sliding-layer transition in the excitonic insulator Ta2NiSe5
Akitoshi Nakano,
Kento Sugawara,
Shinya Tamura,
Naoyuki Katayama,
Kazuyuki Matsubayashi,
Taku Okada,
Yoshiya Uwatoko,
Kouji Munakata,
Akiko Nakao,
Hajime Sagayama,
Reiji Kumai,
Kunihisa Sugimoto,
Naoyuki Maejima,
Akihiko Machida,
Tetsu Watanuki,
Hiroshi Sawa
Affiliations
Akitoshi Nakano
Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
Kento Sugawara
Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
Shinya Tamura
Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
Naoyuki Katayama
Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
Kazuyuki Matsubayashi
University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
Taku Okada
Institute for Solid State Physics (ISSP), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
Yoshiya Uwatoko
Institute for Solid State Physics (ISSP), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
Kouji Munakata
Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
Akiko Nakao
Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
Hajime Sagayama
Photon Factory, IMSS, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
Reiji Kumai
Photon Factory, IMSS, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
Kunihisa Sugimoto
Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Hyogo 679-5198, Japan
Naoyuki Maejima
Synchrotron Radiation Research Center (SRRC), National Institutes for Quantum and Radiological Science and Technology (QST), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
Akihiko Machida
Synchrotron Radiation Research Center (SRRC), National Institutes for Quantum and Radiological Science and Technology (QST), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
Tetsu Watanuki
Synchrotron Radiation Research Center (SRRC), National Institutes for Quantum and Radiological Science and Technology (QST), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
Hiroshi Sawa
Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
The crystal structure of the excitonic insulator Ta2NiSe5 has been investigated under a range of pressures, as determined by the complementary analysis of both single-crystal and powder synchrotron X-ray diffraction measurements. The monoclinic ambient-pressure excitonic insulator phase II transforms upon warming or under a modest pressure to give the semiconducting C-centred orthorhombic phase I. At higher pressures (i.e. >3 GPa), transformation to the primitive orthorhombic semimetal phase III occurs. This transformation from phase I to phase III is a pressure-induced first-order phase transition, which takes place through coherent sliding between weakly coupled layers. This structural phase transition is significantly influenced by Coulombic interactions in the geometric arrangement between interlayer Se ions. Furthermore, upon cooling, phase III transforms into the monoclinic phase IV, which is analogous to the excitonic insulator phase II. Finally, the excitonic interactions appear to be retained despite the observed layer sliding transition.
