7,012 research outputs found
Spin Tunneling, Berry phases and Doped Antiferromagnets
Interference effects between Berry phase factors in spin tunneling systems
have been discussed in recent Letters by Loss, DiVincenzo and Grinstein and von
Delft and Henley. This Comment points out that Berry phases in spin tunneling
are important in another interesting case: the two dimensional doped
antiferromagnet. I show that the dispersion of a single hole in the t-J model
changes sign as where is the size of the spins. This provides
an interpretation of the numerical results for the s=\half model, and a
prediction for other spin sizes.Comment: 5 pages, LaTe
Effects of non-adiabaticity on the voltage generated by a moving domain wall
We determine the voltage generated by a field-driven domain wall, taking into
account non-adiabatic corrections to the motive force induced by the
time-dependent spin Berry phase. Both the diffusive and ballistic transport
regimes are considered. We find that that the non-adiabatic corrections,
together with the contributions due to spin relaxation, determine the voltage
for driving fields smaller than the Walker breakdown limit.Comment: 8 pages, 3 figure
Antiferromagnetic Spinor Condensates are Quantum Rotors
We establish a theoretical correspondence between spin-one antiferromagnetic
spinor condensates in an external magnetic field and quantum rotor models in an
external potential. We show that the rotor model provides a conceptually clear
picture of the possible phases and dynamical regimes of the antiferromagnetic
condensate. We also show that this mapping simplifies calculations of the
condensate's spectrum and wavefunctions. We use the rotor mapping to describe
the different dynamical regimes recently observed in Na condensates. We
also suggest a way to experimentally observe quantum mechanical effects
(collapse and revival) in spinor condensates.Comment: minor revisions. some typos correcte
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