Showing papers by "Akira Fukuda published in 2011"
TL;DR: In this paper, the excitation properties of bilayer fractional quantum Hall (QH) phases were investigated using magnetotransport measurements using a GaAs$/$AlGaAs double-quantum-well sample.
Abstract: We report on novel excitation properties in the \ensuremath{
u} $=$ 2/3 bilayer quantum Hall (QH) phases by carrying out magnetotransport measurements using a GaAs$/$AlGaAs double-quantum-well sample. We refer to the areas with different particular excitation properties in a single phase as phase internal areas (pi-areas). The differences of the excited states between the pi-areas in the high- and low-magnetic-field region of the same phase lead to different behavior of thermal activation energy \ensuremath{\Delta} under a tilted magnetic field. A new pi-area appears between the balanced point and the single-layer region when \ensuremath{\Delta}${}_{\mathrm{SAS}}$ is small. A simple theoretical model based on the composite-fermion picture is advanced for bilayer fractional QH systems to interpret the characteristics of these pi-areas. Finite-size exact-diagonalization calculations are also executed to verify the validity of the theoretical model.
4 citations
TL;DR: DIC）の徴候が認められた．腹部超音波検査ではbright liverではなかったが，急性妊娠性
Abstract: 症例は35歳の女性で切迫早産にて当院産科に入院中であった．妊娠35週6日から急に全身倦怠感と上腹部痛が出現して，急性肝不全，播種性血管内凝固症候群（DIC）の徴候が認められた．腹部超音波検査ではbright liverではなかったが，急性妊娠性脂肪肝と診断されて同日緊急帝王切開術が施行された．しかし，翌日左上腹部痛が増強し，アミラーゼの急上昇が認められた．腹部CTでは膵全体の腫大と膵周辺への炎症の波及が認められた．予後因子3点を満たしたので重症急性膵炎と診断された．保存的治療の経過は良好であり，膵炎診断後18日後には軽快退院となった． 本症例は妊娠時急性膵炎の成因となりうる著明な高脂血症は認められなかった．急性妊娠性脂肪肝は腹腔動脈の攣縮が原因とされる．本症例で合併した急性膵炎も膵臓の栄養動脈の血管攣縮による膵虚血が成因の一つとして考察された．
1 citations
28 Dec 2011
TL;DR: In this article, the authors studied the hysteresis of magnetoresistance in the bilayer ν = 4/3 and monolayer ρ = 2/3 quantum Hall states (QHSs), where ρ is the Landau level filling factor, in order to understand the mechanism of dynamic nuclear polarizations that affects transport properties of GaAs/AlAs two-dimensional electron gas system.
Abstract: We study the hysteresis of magnetoresistance in the bilayer ν = 4/3 and monolayer ν = 2/3 quantum Hall states (QHSs), where ν is the Landau level filling factor, in order to understand the mechanism of dynamic nuclear polarizations (DNPs) that affects transport properties of GaAs/AlAs two-dimensional electron gas system. Basically hysteresis around the bilayer ν = 4/3 is resulted in the monolayer ν = 2/3 in each layer. However, we also find hysteresis that appears around the bilayer ν = 1 QHS region caused by the strong effects of DNPs as a consequence of the sweep over ν = 2/3 QHS in one layer. These findings suggest the effects of nuclear spin polarizations in the bilayer QHSs over a wide range of filling factors.