Staggered Fermion, its Symmetry and Ichimatsu-Patterned Lattice

We investigate exact symmetries of a staggered fermion in D dimensions. The Dirac operator is reformulated by SO(2D) Clifford algebra. The chiral symmetry, rotational invariance and parity symmetries are clarified in any dimension. Local scalar and pseudo-scalar modes are definitely determined, in which we find non-standard modes. The relation to Ichimatsu-patterned lattice approach is discussed.Comment: 3 pages, 1 figure, "Talk at Lattice2004(theory), Fermilab, June 21-26, 2004

Vacuum Structure of the Ichimatsu-Decomposed Lattice Models

We proposed an `Ichimatsu'-decomposed lattice gauge theory with fermionic symmetries. The vacuum structures of the gauge sector with two coupling constants ($\beta_p,\beta_c$) are investigated for 3-dimensional Z$_2$ and 4-dimensional SU(2) cases using mean-field approximation and numerical simulation. We found two phases on the ($\beta_p,\beta_c$) phase diagram for 3-dim. Z$_2$ case, while the diagram is a single phase for the latter.Comment: 3 pages, 6 figures, Lattice2002(higgssusy

Comment on ``Local dimer-adatom stacking fault structures from 3x3 to 13x13 along Si(111)-7x7 domain boundaries''

Zhao et al. [Phys.Rev.B 58, 13824 (1998)] depicted several atomic structures of domain boundaries on a Si(111) surface and criticized the article by the present author and the co-workers. I will point out that their criticism is incorrect and their structure models have no consistency.Comment: 2 pages. Physical Review B, to appea

Presence of 3d Quadrupole Moment in LaTiO3 Studied by 47,49Ti NMR

Ti NMR spectra of LaTiO3 are reexamined and the orbital state of this compound is discussed. The NMR spectra of LaTiO3 taken at 1.5 K under zero external field indicate a large nuclear quadrupole splitting. This splitting is ascribed to the presence of the rather large quadrupole moment of 3d electrons at Ti sites, suggesting that the orbital liquid model proposed for LaTiO3 is inappropriate. The NMR spectra are well explained by the orbital ordering model expressed approximately as $1/\sqrt{3}(d_{xy}+d_{yz}+d_{zx})$ originating from a crystal field effect. It is also shown that most of the orbital moment is quenched.Comment: 4 pages, 3 fugures; to appear in Phys. Rev. Let

Near-Infrared Spectroscopy of Very Low-Luminosity Young Stellar Objects in the Taurus Molecular Cloud

We have carried out near-infrared spectroscopic observations of 23 very low-luminosity young stellar object (YSO) candidates and 5 their companions in Heiles Cloud 2, one of the densest parts of the Taurus molecular cloud. Twelve objects were confirmed as YSOs by Br gamma feature. The effective temperatures of the YSOs and of the companions are estimated from the 2.26 micron feature, the 2.21 micron feature, and the H2O band strengths. Detailed comparisons of our photometric and spectroscopic observations with evolutionary tracks on the HR diagram suggest some objects to be very low-mass YSOs.Comment: 15 pages, 19 figures. PASJ accepte

Atomically straight steps on vicinal Si (111) surfaces prepared by step-parallel current in the kink-up direction

We demonstrate that annealing of a vicinal Si(111) surface at about 800 C with a direct current in the direction that ascends the kinks enhances the formation of atomically straight step edges over micrometer lengths, while annealing with a current in the opposite direction does not. Every straight step edge has the same atomic configuration U(2,0), which is useful as a template for the formation of a variety of nanostructures. A phenomenological model based on electromigration of charged mobile atoms explains the observed current-polarity dependent behavior.Comment: Accepted for publication in Appl. Phys. Lett. Numbers of pages and figures are 12 and 4, respectivel