Published in:

Physical Review B 78,5 ( 2008 )


We calculate the expected finite frequency neutron-scattering intensity based on the two-sublattice collinear antiferromagnet found by recent neutron-scattering experiments as well as by theoretical analysis on the iron oxypnictide LaOFeAs. We consider two types of superexchange couplings between Fe atoms: nearest-neighbor coupling J(1) and next-nearest-neighbor coupling J(2). We show how to distinguish experimentally between ferromagnetic and antiferromagnetic J(1). Whereas magnetic excitations in the cuprates display a so-called resonance peak at (pi, pi) (corresponding to a saddlepoint in the magnetic spectrum), which is at a wave vector that is at least close to nesting Fermi-surface-like structures-no such corresponding excitations exist in the iron pnictides. Rather, we find saddlepoints near (pi, pi/2) and (0, pi/2) (and symmetry related points), which are not close to nesting the Fermi surfaces.


Physics, Condensed Matter

Date of this Version

January 2008



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.