Three-dimensional electronic structures and the metal-insulator transition in Ruddlesden-Popper iridates

Yamasaki, Atsushi*; Fujiwara, Hidenori*; Tachibana, Shoichi*; Iwasaki, Daisuke*; Higashino, Yuji*; Yoshimi, Chiaki*; Nakagawa, Koya*; Nakatani, Yasuhiro*; Yamagami, Kohei*; Aratani, Hidekazu*; et al.

Physical Review B, 94(11), p.115103_1 - 115103_10, 2016/11

AA2016-0587.pdf:2.55MB

https://doi.org/10.1103/PhysRevB.94.115103

In this study, we systematically investigate three-dimensional(3D) momentum-resolved electronic structures of Ruddlesden-Popper-type iridium oxides SrIrO using soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES). Our results provide direct evidence of an insulator-to-metal transition that occurs upon increasing the dimensionality of the IrO-plane structure. This transition occurs when the spin-orbit-coupled = 1/2 band changes its behavior in the dispersion relation and moves across the Fermi energy. By scanning the photon energy over 350 eV, we reveal the 3D Fermi surface in SrIrO and -dependent oscillations of photoelectron intensity in SrIrO. To corroborate the physics deduced using low-energy ARPES studies, we propose to utilize SX-ARPES as a powerful complementary technique, as this method surveys more than one whole Brillouin zone and provides a panoramic view of electronic structures.

Momentum-resolved electronic excitations in the Mott insulator SrIrO studied by resonant inelastic X-ray scattering

Ishii, Kenji; Jarrige, I.; Yoshida, Masahiro; Ikeuchi, Kazuhiko*; Mizuki, Junichiro; Ohashi, Kei*; Takayama, Tomohiro*; Matsuno, Jobu*; Takagi, Hidenori*

Physical Review B, 83(11), p.115121_1 - 115121_5, 2011/03

https://doi.org/10.1103/PhysRevB.83.115121

Local structure anomaly around Ge dopants in MnCuGeN with negative thermal expansion

Matsuno, Jobu*; Takenaka, Koshi*; Takagi, Hidenori*; Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro

Applied Physics Letters, 94(18), p.181904_1 - 181904_3, 2009/05

https://doi.org/10.1063/1.3129169

Local structure analysis of Cu and Ge atoms in the negative thermal expansion material MnCuGeN was conducted using X-ray absorption fine structure measurements. The temperature dependence of the interatomic distance was found to reflect the macroscopic negative thermal expansion both for Cu-Mn and Ge-Mn shells, although the magnitude of the relative change was much larger for Ge-Mn than Cu-Mn. An enhanced anomaly of the Debye-Waller factor was observed for the Ge-Mn shell in the temperature region of the negative expansion, indicating the presence of static local disorder around Ge impurities. These local structure anomalies strongly suggest that the local and inhomogeneous strain around Ge is essential in broadening the discontinuous volume contraction.