Dissipationless Spin Current Generation in Kitaev's Chiral Spin Liquid

$\alpha$-RuCl$_3$ is a promising candidate material for the Kitaev spin liquid state where the half quantization of the thermal Hall effect, suggesting a topological character, has been observed. However, its relation to the existence of chiral Majorana fermions, which is predicted from the theory of the Kitaev model, is still under debate. Here we propose a more direct signature of a chiral Majorana edge mode which emerges in a universal scaling of the Drude weight of the edge spin Seebeck effect in the Kitaev model. Moreover, the absence of backscatterings in the chiral edge mode results in the generation of a dissipationless spin current in spite of an extremely short spin correlation length close to a lattice constant in the bulk. This result is not only experimentally observable, but also opens a way towards spintronics application of Kitaev materials. In contrast to magnetically ordered systems, a Kitaev spin liquid state is stable even in the atomic scale and makes it possible to fabricate a highly integrated device with substantial efficiency to generate a spin current. This proposal for using $\alpha$-RuCl$_3$ as a nano-scale device will pioneer Kitaev spintronics.Comment: 8 pages, 4 figure

EM Attack Is Non-Invasive? - Design Methodology and Validity Verification of EM Attack Sensor

This paper presents a standard-cell-based semi-automatic design methodology of a new conceptual countermeasure against electromagnetic (EM) analysis and fault-injection attacks. The countermeasure namely EM attack sensor utilizes LC oscillators which detect variations in the EM field around a cryptographic LSI caused by a micro probe brought near the LSI. A dual-coil sensor architecture with an LUT-programming-based digital calibration can prevent a variety of microprobe-based EM attacks that cannot be thwarted by conventional countermeasures. All components of the sensor core are semi-automatically designed by standard EDA tools with a fully-digital standard cell library and hence minimum design cost. This sensor can be therefore scaled together with the cryptographic LSI to be protected. The sensor prototype is designed based on the proposed methodology together with a 128bit-key composite AES processor in 0.18um CMOS with overheads of only 1.9% in area, 7.6% in power, and 0.2% in performance, respectively. The validity against a variety of EM attack scenarios has been verified successfully

風力発電用カイトの空力特性

修士（工学

Synthesis and Electrochemical Performance of LiMnPO4 by Hydrothermal Method

LiMnPO4 with olivinestructure which is the promising candidate for high voltage cathode material was synthesized by hydrothermal method. In order to synthesize high purity and well-defined LiMnPO4, several precursors for Li, Mn, and P sources and hydrothermal reaction parameters including temperature and [H2O]/[Mn] value are optimized. By analyzing the structure, Mn valence, morphology, and chemical ratio via XRD, XPS, Raman, SEM, and ICP LiMnPO4 synthesized from manganese acetate tetrahydrate have single phase of LiMnPO4 without impurity and showed charge and discharge reaction caused by Mn2+/Mn3+ redox. Specific capacity of synthesized LiMnPO4 grew up during cycling. Moreover, when hydrothermal temperature was set at 150°C and [H2O]/[Mn] value was set at 15, discharge capacity as high as 70 mAh/g was obtained at 1/20  C rate

Synthesis of Tetra‐Substituted Trifluoromethyl‐3,1‐Benzoxazines by Transition‐Metal‐Catalyzed Decarboxylative Cyclization of N‐Benzoyl Benzoxazinones

Abstract Efficient synthesis of N,O‐heterocyclic tetra‐substituted trifluoromethyl‐3,1‐benzoxazines via a transition‐metal‐catalyzed decarboxylative intramolecular cyclization was achieved. The decarboxylation of N‐benzoyl trifluoromethyl‐benzoxazinones generated the amide oxygen nucleophile, allowing a selective internal C1‐attack on Pd‐ or Cu‐coordinated zwitterions, affording medicinally attractive tetra‐substituted vinyl‐ or ethynyl‐trifluoromethyl‐3,1‐benzoxazines. This protocol can be applied to the synthesis of perfluoroalkyl‐ and non‐fluorinated 3,1‐benzoxazines