47,449 research outputs found
Evidence of spin liquid with hard-core bosons in a square lattice
We show that laser assisted hopping of hard core bosons in a square optical
lattice can be described by an antiferromagnetic - XY model with
tunable ratio of . We numerically investigate the phase diagram of
the - XY model using both the tensor network algorithm for
infinite systems and the exact diagonalization for small clusters and find
strong evidence that in the intermediate region around ,
there is a spin liquid phase with vanishing magnetization and valence bond
orders, which interconnects the Neel state on the side and the
stripe antiferromagnetic phase on the side. This finding
opens up the possibility of studying the exotic spin liquid phase in a
realistic experimental system using ultracold atoms in an optical lattice.Comment: 5 pages, 5 figure
Supersolid and charge density-wave states from anisotropic interaction in an optical lattice
We show anisotropy of the dipole interaction between magnetic atoms or polar
molecules can stabilize new quantum phases in an optical lattice. Using a well
controlled numerical method based on the tensor network algorithm, we calculate
phase diagram of the resultant effective Hamiltonian in a two-dimensional
square lattice - an anisotropic Hubbard model of hard-core bosons with
attractive interaction in one direction and repulsive interaction in the other
direction. Besides the conventional superfluid and the Mott insulator states,
we find the striped and the checkerboard charge density wave states and the
supersolid phase that interconnect the superfluid and the striped solid states.
The transition to the supersolid phase has a mechanism different from the case
of the soft-core Bose Hubbard model.Comment: 5 pages, 5 figures
Kinetics and mechanism of formic acid decomposition on Ru(001)
The steady-state rate of decomposition of formic acid on
Ru(001) has been measured as a function of surface temperature, parametric in the pressure of formic acid. The
products of the decomposition reaction are C0_2, H_2, CO,
and H_2)0, i.e., both dehydrogenation and dehydration occur
on Ru (001). A similar product distribution has been observed on Ni(110), Ni(100), Ru(100), Fe(100), and
Ni(111) surfaces; whereas only dehydrogenation to C0_2
and H_2 occurs on the Cu(100), Cu(110), and Pt(111)
surfaces. Only reversible adsorption and desorption of formic acid is observed on the less reactive Ag(110) surface at low temperatures, whereas the more reactive Mo(100) surface is oxidized by formic acid at low temperatures with the products of this reaction being H_2, CO, and H_(2)O (Ref. 10). We report here the confirmation of earlier observations of the occurrence of both dehydrogenation and dehydration of formic acid on Ru(001), and more importantly, we provide a detailed mechanistic description of the steady-state decomposition reaction on this surface in terms of elementary steps
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