8,084 research outputs found
Hidden spin current in doped Mott antiferromagnets
We investigate the nature of doped Mott insulators using exact
diagonalization and density matrix renormalization group methods. Persistent
spin currents are revealed in the ground state, which are concomitant with a
nonzero total momentum or angular momentum associated with the doped hole. The
latter determines a nontrivial ground state degeneracy. By further making
superpositions of the degenerate ground states with zero or unidirectional spin
currents, we show that different patterns of spatial charge and spin
modulations will emerge. Such anomaly persists for the odd numbers of holes,
but the spin current, ground state degeneracy, and charge/spin modulations
completely disappear for even numbers of holes, with the two-hole ground state
exhibiting a d-wave symmetry. An understanding of the spin current due to a
many-body Berry-like phase and its impact on the momentum distribution of the
doped holes will be discussed.Comment: 9 pages, 9 figures, update second version including more data and
discussion adde
Libration Orbit Eclipse Avoidance Maneuver Study for the James Webb Space Telescope Mission
Mission analysis of libration orbit trajectories at Sun-Earth/Moon L2 typically includes predictions of lunar and Earth eclipses during the mission life-time. The NASA James Webb Space Telescope (JWST) trajectory, by design, avoids these eclipses by pruning its launch window. In an off-nominal scenario where an eclipse is predicted, a maneuver strategy is needed. In this paper, trade studies are examined for JWST that characterize the burn magnitude, location, and epochs of multiple maneuver plans to avoid an eclipse. The results enable analysts to explore the space of feasible maneuver strategies during routine operations
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