1202.3676 (J. M. Caron et al.)

Orbital Selective Magnetism in the Spin-Ladder Iron Selenides
Ba$_{1-x}$K$_{x}$Fe$_2$Se$_3$    [PDF]

J. M. Caron, J. R. Neilson, D. C. Miller, K. Arpino, A. Llobet, T. M. McQueen

In this letter we show that the 2.80(8) {\mu}B/Fe block antiferromagnetic
order of BaFe2Se3 transforms into stripe antiferromagnetic order in KFe2Se3
with a decrease in moment to 2.1(1) {\mu}B/Fe. This reduction is larger than
expected from the change in electron count from Ba$^{2+}$ to K$^{+}$, and
occurs with the loss of the displacements of Fe atoms from ideal positions in
the ladders, as found by neutron pair distribution function analysis.
Intermediate compositions remain insulating, and magnetic susceptibility
measurements show a suppression of magnetic order. Together, these results
imply an orbital-dependent selection of magnetic versus bonded behavior, driven
by relative bandwidths and fillings.

View original: http://arxiv.org/abs/1202.3676