Topic
Spin-½
About: Spin-½ is a research topic. Over the lifetime, 40423 publications have been published within this topic receiving 796639 citations.
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TL;DR: The quantum Hall (QH) effect in two-dimensional electrons and holes in high quality graphene samples is studied in strong magnetic fields up to 45 T and can be attributed to lifting of the spin degeneracy of the n = 1 Landau level.
Abstract: The quantum Hall (QH) effect in two-dimensional electrons and holes in high quality graphene samples is studied in strong magnetic fields up to 45 T. QH plateaus at filling factors nu = 0, +/-1, +/-4 are discovered at magnetic fields B > 20 T, indicating the lifting of the fourfold degeneracy of the previously observed QH states at nu = +/-4(absolute value(n) + 1/2), where n is the Landau-level index. In particular, the presence of the nu = 0, +/-1 QH plateaus indicates that the Landau level at the charge neutral Dirac point splits into four sublevels, lifting sublattice and spin degeneracy. The QH effect at nu = +/-4 is investigated in a tilted magnetic field and can be attributed to lifting of the spin degeneracy of the n = 1 Landau level.
636 citations
TL;DR: The present combined work of transport measurement, neutron scattering, and theoretical calculation provides evidence that the gigantic anomalous Hall effect observed in Nd 2 Mo 2 O 7, a pyrochlore ferromagnet with geometrically frustrated lattice structure, is mostly due to the spin chirality and the associated Berry phase originating from the Mo spin tilting as mentioned in this paper.
Abstract: An electron hopping on non-coplanar spin sites with spin chirality obtains a complex phase factor (Berry phase) in its quantum mechanical amplitude that acts as an internal magnetic field, and is predicted to manifest itself in the Hall effect when it is not cancelled The present combined work of transport measurement, neutron scattering, and theoretical calculation provides evidence that the gigantic anomalous Hall effect observed in Nd 2 Mo 2 O 7 , a pyrochlore ferromagnet with geometrically frustrated lattice structure, is mostly due to the spin chirality and the associated Berry phase originating from the Mo spin tilting
635 citations
TL;DR: This work considers the various asymmetries, notably single spin asymmetry, that appear in leptoproduction as a consequence of the presence of time-reversal odd distribution functions, which could facilitate experimental searches for time-REVERSal odd phenomena.
Abstract: We consider the various asymmetries, notably single spin asymmetries, that appear in leptoproduction as a consequence of the presence of time-reversal odd distribution functions. This could facilitate experimental searches for time-reversal odd phenomena.
635 citations
TL;DR: In this paper, the structure of the set of superselection sectors (charge quantum numbers) and its implications for the particle aspects of the theory are studied. And the scattering states and transition probabilities are obtained in this frame.
Abstract: Starting from the principles of local relativistic Quantum Theory without long range forces, we study the structure of the set of superselection sectors (charge quantum numbers) and its implications for the particle aspects of the theory. Without assuming the commutation properties (or even the existence) of unobservable fields connecting different sectors (charge-carrying fields), one has a particle-antiparticle symmetry, an intrinsic notion of statistics for identical particles, and a spin-statistics theorem. Particles in “pseudoreal sectors” cannot be their own antiparticles (a variant of Carruthers' theorem). We also show how scattering states and transition probabilities are obtained in this frame.
634 citations
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19 Apr 2006
TL;DR: In this article, it was shown that the dispersion relation is periodic in the momentum of the magnons and that the symmetries that determine this relation are the same in the gauge theory and the string theory.
Abstract: Studies of ${\cal N}=4$ super Yang Mills operators with large R-charge have shown that, in the planar limit, the problem of computing their dimensions can be viewed as a certain spin chain These spin chains have fundamental ``magnon'' excitations which obey a dispersion relation that is periodic in the momentum of the magnons This result for the dispersion relation was also shown to hold at arbitrary 't Hooft coupling Here we identify these magnons on the string theory side and we show how to reconcile a periodic dispersion relation with the continuum worldsheet description The crucial idea is that the momentum is interpreted in the string theory side as a certain geometrical angle We use these results to compute the energy of a spinning string We also show that the symmetries that determine the dispersion relation and that constrain the S-matrix are the same in the gauge theory and the string theory We compute the overall S-matrix at large 't Hooft coupling using the string description and we find that it agrees with an earlier conjecture We also find an infinite number of two magnon bound states at strong coupling, while at weak coupling this number is finite
629 citations