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Single Crystal Growth and Physical Properties of UT2Al20 (T=Transition Metal)
Yuji Matsumoto,Tatsuma D. Matsuda,Naoyuki Tateiwa,Etsuji Yamamoto,Yoshinori Haga,Zachary Fisk 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We have studied the single crystal growth and the physical properties of the UT2Al20 system. Wehave successfully grown UT2Al20 (T = Cr, Ti, W and Mo) using Al self flux and have characterizedthe crystals using electron probe microanalyzer (EPAM) and X-ray diffractometer. We have alsomeasured their magnetic and electric properties. The ground states of UT2Al20 (T = Cr, Mo andW ) are Pauli paramagnetic as is likely also in UTi2Al20. The effective masses of UCr2Al20 andUTi2Al20 are only weakly enhanced.
Naoyuki Tateiwa,Yoshinori Haga,Tatsuma D. Matsuda,Etsuji Yamamoto,Yoshichika Onuki,Zachary Fisk 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We have studied the high-pressure magnetic property in UGe2 where ferromagnetic superconductivityappears under high pressure. In this study, we focus on the magnetic property at pressuresabove the ferromagnetic critical pressure Pc =1.6 GPa. The temperature and magnetic field dependencesof the dc-magnetization have been measured under high pressures up to 5.1 GPa by using aceramic anvil high pressure cell. At pressures above Pc, the magnetic susceptibility χ shows a broadmaximum around Tχmax and the magnetization at 2.0 K shows an abrupt increase (metamagnetictransition) at Hc. With increasing pressure, the peak structure in χ becomes broader, and thepeak position Tχmax moves to the higher temperature region. The metamagnetic field Hc increasesrapidly with increasing pressure. At pressures above 4.1 GPa, χ shows a simple temperature dependence,and the magnetization increases linearly with increasing field. These phenomena in UGe2resemble to those in the intermetallic compounds of 3d transition metals such as Co(S1−xSex) andYCo2. We discuss the experimental results by using the phenomenological spin-fluctuation theory.
Magnetic Phase Diagram of UCoAl
Tatsuma D. Matsuda,Naoyuki Tateiwa,Etsuji Yamamoto,Yoshinori Haga,Yoshichika Onuki,Dai Aoki,Jacques Flouquet,Zachary Fisk 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We report precision c-axis magnetic measurements on a high-quality single crystal of the heavyfermion metamagnet UCoAl. The metamagnetic transition at HM changes from 1st order at lowtemperature to a crossover at high temperature. HM is nearly linearly increasing with increasingtemperature up to a critical temperature T0. The critical temperature T0 is determined from boththe field and the temperature dependences of magnetization to be 11 K. The field dependence ofthe Sommerfeld coefficientis estimated from M(T) by using a Maxwell relation. (H) shows astep-like decrease at HM. This behavior is consistent with the previous reports of specific heat andresistivity measurements at low temperatures.
Yoshichika Onuki,Rikio Settai,Kiyohiro Sugiyama,Tetsuya Takeuchi,Fuminori Honda,Yoshinori Haga,Etsuji Yamamoto,Tatsuma D. Matsuda,Naoyuki Tateiwa,Dai Aoki,Ilya Sheikin,Hisatomo Harima 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
The f-electron system in rare-earth and actinide compounds exhibit a variety of characteristicproperties including heavy fermions and unconventional superconductivity. The Fermi surface propertiesin rare-earth and actinide compounds are clarified by the de Haas-van Alphen experimentson the basis of the results of energy band calculations. The effect of pressure on the electronicstates of CeRhIn5, CeIrSi3, and YbIr2Zn20 is studied in magnetic fields. An electronic instability,including unconventional superconductivity, occurs at 2.4 GPa in CeRhIn5 and 2.6 GPa in CeIrSi3. An abrupt non-linear increase in the magnetization, namely, a metamagnetic behavior, is found inthe heavy fermion compounds, including YbT2Zn20 (T: Co, Rh, Ir). A super-heavy fermion statewith a specific heat coefficient of 10 J/(K2·mol) is realized in YbIr2Zn20 under pressure.
Pressure Evolution of the Metamagnetic Transition in UCoAl As Measured Using 59Co NMR
Hisashi Kotegawa,Hiroki Nohara,Hideki Tou,Tatsuma D. Matsuda,Etsuji Yamamoto,Yoshinori Haga,Zachary Fisk,Yoshichika Onuki,Dai Aoki,Jacques Flouquet 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We have performed NMR measurements under pressure in UCoAl with a quantum critical endpointof the metamagnetic transition from the paramagnetic phase to the ferromagnetic (FM) phase. 59Co-NMR sensitively detects the evolution of the internal field caused by applying the externalfield. The metamagnetic field Hm increases with increasing pressure consistently with other experimentalmethods, accompanied by the suppression of the magnetization in the field-induced FMphase and the magnetization jump at Hm. The loss of the NMR signal on approaching the QCEPindicates the development of the spin fluctuations.
Osawa, Kayo,Nakarai, Chiaki,Akiyama, Minami,Hashimoto, Ryuta,Tsutou, Akimitsu,Takahashi, Juro,Takaoka, Yuko,Kawamura, Shiro,Shimada, Etsuji,Tanaka, Kenichi,Kozuka, Masaya,Yamamoto, Masahiro,Kido, Yosh Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.5
Genetic polymorphisms of uridine diphosphate-glucuronosyltransferases 1A6 (UGT1A6) and 1A7 (UGT1A7) may lead to genetic instability and colorectal cancer carcinogenesis. Our objective was to measure the interaction between polymorphisms of these repair genes and tobacco smoking in colorectal cancer (CRC). A total of 68 individuals with CRC and 112 non-cancer controls were divided into non-smoker and smoker groups according to pack-years of smoking. Genetic polymorphisms of UGT1A6 and UGT1A7 were examined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We found a weak association of UGT1A6 polymorphisms with CRC risk (crude odds ratio [OR], 1.65;95% confidence interval [95% CI], 0.9-3.1, P=0.107; adjusted OR 1.95%, 95% CI 1.0-3.8, P=0.051). The ORs for the UGT1A7 polymorphisms were statistically significant (crude OR: 26.40, 95% CI: 3.5-198.4, P=0.001; adjusted OR: 21.52, 95% CI: 2.8-164.1, P=0.003). The joint effect of tobacco exposure and UGTIA6 polymorphisms was significantly associated with colorectal cancer risk in non-smokers (crude OR, 2.11; 95% CI, 0.9-5.0, P=0.092; adjusted OR 2.63, 95% CI, 1.0-6.7, P=0.042). In conclusion, our findings suggest that UGT1A6 and UGT1A7 gene polymorphisms are associated with CRC risk in the Japanese population. In particualr, UGT1A6 polymorphisms may strongly increase CRC risk through the formation of carcinogens not associated with smoking.