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Anisotropic Spin Excitations in Spin-Peierls CuGeO3
Kazuhiko Ikeuchi,Ryoichi Kajimoto,Fumio Mizuno,Masaki Fujita,Yasuhiro Inamura,Mitsutaka Nakamura,Kenji Nakajima,Kazuya Aizawa,Masatoshi Arai 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We report on the investigation of spin excitations in CuGeO3 at a low temperature by usinginelastic neutron scattering on a pulsed source with a time-of-flight analysis. By observing thedispersion relation of spin excitations not only along the chain direction but also along the interchain direction, we studied spin correlations in the S = 1/2 Heisenberg chains, as well as between thechains, in detail. The results show a clear anisotropy of the magnetic excitations at a temperaturebelow the spin-Peierls transition temperature.
( Takao Itoi ),( Eigoro Yamanouchi ),( Nobuhito Ikeuchi ),( Kazuhiko Kasuya ),( Hitoshi Iwamoto ),( Akihiko Tsuchida ) The Editorial Office of Gut and Liver 2010 Gut and Liver Vol.4 No.s1
Magnetic compression anastomosis (MCA) is a minimally invasive method of performing choledochocholedochostomy without surgery in patients with biliary stricture or obstruction. We describe a successful case involving magnetic compression duct-to-duct biliary reconstruction in right-lobe living donor liver transplantation (RL-LDLT). Endoscopically, a samarium-cobalt (Sm- Co) rare-earth magnet was placed at the superior site of obstruction via the percutaneous transhepatic biliary drainage route, and another Sm-Co magnet was also placed at the inferior site of obstruction with the aid of an endoscope. MCA techniques enabled complete anastomosis without procedure-related complications. In conclusion, the MCA technique is a revolutionary method of performing choledochocholedochostomy in patients with biliary obstruction after LDLT. (Gut Liver 2010;4(Suppl. 1):S96-98)
High-energy Magnetic Excitations in Underdoped La1.90Sr0.10CuO4
Kentaro Sato,Masato Matsuura,Masaki Fujita,Ryoichi Kajimoto,Sungdae Ji,Kazuhiko Ikeuchi,Mitsutaka Nakamura,Yasuhiro Inamura,Masatoshi Arai,Masanori Enoki,Kazuyoshi Yamada 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
We measured the magnetic excitations in underdoped (UD) La1.90Sr0.10CuO4 by using inelasticneutron scattering over a wide energy range. We succeeded in observing the high-energy excitationsup to '160 meV. Hour-glass-like magnetic excitation, which is commonly seen in the superconductingphase of cuprate oxides, was confirmed. The Ecross (the energy where the dispersion is closestto the ( 12 , 12 ) reciprocal position) of 40 meV follows a linear relation between Ecross and the dopedhole concentration in the UD region. From the dispersion of high-energy excitations above Ecross,we successfully found an effective nearest neighbor interaction (Jeff ) of 102 ± 2 meV. This Jeff issmaller than the nearest neighbor interaction J(=132 meV) in the parent compound La2CuO4,indicating a reduction of Jeff by hole-doping.
Masatoshi Sato,Yoshiaki Kobayashi,Takayuki Kawamata,Yukio Yasui,Kazunori Suzuki,M. Itoh,Ryoichi Kajimoto,Kazuhiko Ikeuchi,M. Arai,Phillipe Bourges 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
To identify the superconducting symmetry of Fe-based superconductors, we studied effects ofnonmagnetic-impurities on Tc, magnetic excitation spectra 00 and NMR 1/T1 − T curve, whichare sensitive to the relative signs between the order parameters on the disconnected Fermi surfacesin reciprocal space, because the symmetry is closely connected with the pairing mechanism:If the signs are opposite (symmetry S±), the mechanism is considered to be a magneticone, but when the signs are the same (symmetry S++), a novel mechanism is plausible becausethe ordinary phonon mechanism cannot realize the Tc value as high as 55 K found in Ln1111(Ln=lanthanide). Results are as follows: (a) The very small rates of Tc-suppression by impurityatoms M of LnFe1−yMyAs0.89−xF0.11+x (M=Ni, Co, Ru) can be explained only by S++. (b) The00-data for Ba(Fe, Co)2As2 (Tc 23 K) and Ca-Fe-Pt-As crystals seem to be well explained byS++ rather than by S±. (c) The nuclear magnetic resonance data can be consistently understoodby S++, too. These results suggest the S++ symmetry and a novel pairing mechanism, which canbe considered to be related to the elastic softening of C66 induced by the orbital fluctuation of thesystem.