Jobu Matsuno
National Institute of Advanced Industrial Science and Technology
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Featured researches published by Jobu Matsuno.
Nature Physics | 2016
Kouta Kondou; R. Yoshimi; Atsushi Tsukazaki; Yasuhiro Fukuma; Jobu Matsuno; K. S. Takahashi; Masashi Kawasaki; Y. Tokura; Y. Otani
The spin–momentum locking of Dirac surface states offers intriguing possibilities for converting between charge and spin currents. Experiments show that fine tuning of the Fermi level is critical for maximizing the efficiency of such conversions.
Physical Review Letters | 2015
Jobu Matsuno; Kota Ihara; Shugen Yamamura; H. Wadati; Kenji Ishii; V. Vijay Shankar; Hae-Young Kee; Hidenori Takagi
In 5d Ir oxides with an interplay of spin-orbit coupling and electron correlations, we have tailored a spin-orbital magnetic insulator out of a semimetal SrIrO(3) by tuning the structure through superlattices [(SrIrO(3))(m), SrTiO(3)] (m=1,2,3,4, and ∞). We observed the systematic decrease of the magnetic ordering temperature and the resistivity as a function of m. The transition from the semimetal to the insulator is found to be closely linked to the appearance of magnetism at m≃3. Long range magnetic ordering was realized even in the m=1 single layer superlattice, implying that the design and realization of novel electronic phases is feasible at the level of a single atomic layer in complex Ir oxides.
Science Advances | 2016
Jobu Matsuno; Naoki Ogawa; Kenji Yasuda; Fumitaka Kagawa; Wataru Koshibae; Naoto Nagaosa; Yoshinori Tokura; Masashi Kawasaki
Electronic transport measurements reveal the formation of swirling spin textures, skyrmions, at high-quality oxide interface. Electron transport coupled with magnetism has attracted attention over the years. Among them, recently discovered is topological Hall effect (THE), originating from scalar spin chirality, that is, the solid angle subtended by the spins. THE is found to be a promising tool for probing the Dzyaloshinskii-Moriya (DM) interaction and consequent magnetic skyrmions. This interaction arises from broken inversion symmetry and hence can be artificially introduced at interface; this concept is lately verified in metal multilayers. However, there are few attempts to investigate such DM interaction at interface through electron transport. We clarified how the transport properties couple with interface DM interaction by fabricating the epitaxial oxide interface. We observed THE in epitaxial bilayers consisting of ferromagnetic SrRuO3 and paramagnetic SrIrO3 over a wide region of both temperature and magnetic field. The magnitude of THE rapidly decreases with the thickness of SrRuO3, suggesting that the interface DM interaction plays a significant role. Such interaction is expected to realize a 10-nm-sized Néel-type magnetic skyrmion. The present results established that the high-quality oxide interface enables us to tune the effective DM interaction; this can be a step toward future topological electronics.
Physical Review Letters | 2012
Shigeki Fujiyama; Hiroyuki Ohsumi; T. Komesu; Jobu Matsuno; B. J. Kim; Masaki Takata; T. Arima; Hidenori Takagi
The dynamical correlations of J(eff)=1/2 isospins in the paramagnetic state of spin-orbital Mott insulator Sr2IrO4 were revealed by resonant magnetic x-ray diffuse scattering. We found a two-dimensional antiferromagnetic fluctuation with a large in-plane correlation length exceeding 100 lattice spacings at even 20 K above the magnetic ordering temperature. In marked contrast to the naive expectation of the strong magnetic anisotropy associated with an enhanced spin-orbit coupling, we discovered an isotropic isospin correlation that is well described by the two-dimensional S=1/2 quantum Heisenberg model. The estimated antiferromagnetic coupling constant as large as J∼0.1u2009u2009eV that is comparable to the small Mott gap (<0.5u2009u2009eV) points out the weak and marginal Mott character of this spin-orbital entangled system.
Applied Physics Letters | 2007
Akihito Sawa; Atsushi Yamamoto; Hideaki Yamada; Tetsu Fujii; M. Kawasaki; Jobu Matsuno; Y. Tokura
The authors have studied electrical properties of perovskite heteroepitaxial junctions consisting of transition metal oxides La1−xSrxMO3 (LSMO: M=Mn, Fe, Co, and Ni) and an n-type semiconductor SrTi0.99Nb0.01O3 (Nb:STO). The junctions showed rectifying current-voltage characteristics that could be analyzed by taking into account a Schottky-like barrier formed in the Nb:STO at the interfaces. As the doping level x is increased, the Schottky barrier height and built-in potential increase as ∼x (eV), indicating the downward shift of the Fermi level position in the LSMO. The Fermi level position in the LSMO with the same doping level x tends to be deepened with increasing the atomic number of M, in the order of Mn, Fe, Co, and Ni.
Nature Communications | 2013
Kohei Fujiwara; Yasuhiro Fukuma; Jobu Matsuno; Hiroshi Idzuchi; Yasuhiro Niimi; Y. Otani; Hidenori Takagi
Devices based on pure spin currents have been attracting increasing attention as key ingredients for low-dissipation electronics. To integrate such spintronics devices into charge-based technologies, electric detection of spin currents is essential. The inverse spin Hall effect converts a spin current into an electric voltage through spin-orbit coupling. Noble metals such as Pt and Pd, and also Cu-based alloys, have been regarded as potential materials for a spin-current injector, owing to the large direct spin Hall effect. Their spin Hall resistivity ρSH, representing the performance as a detector, is not large enough, however, due mainly because of their low charge resistivity. Here we report that a binary 5d transition metal oxide, iridium oxide, overcomes the limitations encountered in noble metals and Cu-based alloys and shows a very large ρSH~38 μΩ cm at room temperature.
Applied Physics Letters | 2008
Jobu Matsuno; Akihito Sawa; Masashi Kawasaki; Yoshinori Tokura
We have investigated epitaxial Nd0.5Sr0.5MnO3∕SrTi0.9998Nb0.0002O3(110) (NSMO/Nb:STO) junctions wherein a metal-insulator transition can be induced by magnetic field in the NSMO layer. The NSMO/Nb:STO junctions show highly rectifying current density–voltage (J-V) characteristics, in accord with the conventional theory for a Schottky (or a p-n) diode. The forward bias J-V, as well as the reverse bias capacitance-voltage characteristics, has revealed a built-in potential of 0.8–0.9eV. In the reverse bias region, a large positive magnetocapacitance has been observed at 5 and 50K, suggesting that the effective carrier density of NSMO is modified by the magnetic field.
APL Materials | 2015
Daigorou Hirai; Jobu Matsuno; Hidenori Takagi
We report the fabrication of (111)-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3) of Ca0.5Sr0.5IrO3 perovskite and two layers of SrTiO3 perovskite on SrTiO3(111) substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.
Physical Review B | 2016
A. Yamasaki; H. Fujiwara; S. Tachibana; D. Iwasaki; Y. Higashino; C. Yoshimi; K. Nakagawa; Y. Nakatani; Kohei Yamagami; H. Aratani; Ozan Kirilmaz; M. Sing; R. Claessen; H. Watanabe; Tomonori Shirakawa; Seiji Yunoki; A. Naitoh; Kouichi Takase; Jobu Matsuno; Hidenori Takagi; Akira Sekiyama; Y. Saitoh
In this study, we systematically investigate 3D momentum(
Applied Physics Letters | 2015
Daigorou Hirai; Jobu Matsuno; Daisuke Nishio-Hamane; Hidenori Takagi
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