Dynamic nuclear polarization and Knight shift measurements in a breakdown regime of integer quantum Hall effect

Nuclear spins are polarized electrically in a breakdown regime of an odd-integer quantum Hall effect (QHE). Electron excitation to the upper Landau subband with the opposite spin polarity flips nuclear spins through the hyperfine interaction. The polarized nuclear spins reduce the spin-splitting energy and accelerate the QHE breakdown. The Knight shift of the nuclear spins is also measured by tuning electron density during the irradiation of radio-frequency magnetic fields.Comment: 3 pages, 2 figures, EP2DS-1

オケルマナイト ハーディストナイトケイ コヨウタイ ノ ゴウセイ

Studies on formation, thermal reaction and lattice dimensions of solid solutions in the system akermanite (Ca_2MgSi_2O_7)-hardystonite (Ca_2ZnSi_2O_7) have been carried out by DTA and X-ray powder diffraction on the products which were prepared by solid-state reaction using CaCO_3,MgO, ZnO and SiO_2 as starting materials. Åkermanite and hardystonite were preferably synthesized with double heatings at 1,330℃ and 1,250℃, respectively. The solid solutions were done at the intermediate temperatures in proportion to Mg/Zn of solid solutions. From akermanite to hardystonite, the melting points changed from 1,462℃ to 1,432℃ with approximately linear line. Further, the unit tetragonal cell constants, a_0 and c_0,changed linearly from 7.8328 and 5.0081 (Å) to 7.8250 and 5.0166 (Å), respectively. It is concluded that the solid solutions in the system akermanite-hardystonite form a complete series of solid solution by isomorphous replacement of Mg by Zn