  The microscopic structure of a charge stripe in an antiferromagnetic
insulator is studied within the t-Jz model using analytical and numerical
approaches. We demonstrate that a stripe in an antiferromagnet should be viewed
as a system of composite holon-spin-polaron excitations condensed at the
self-induced antiphase domain wall (ADW) of the antiferromagnetic spins. The
properties of such excitations are studied in detail with numerical and
analytical results for various quantities being in very close agreement. A
picture of the stripe as an effective one-dimensional (1D) band of such
excitations is also in very good agreement with numerical data. These results
emphasize the primary role of kinetic energy in favoring the stripe as a ground
state. A comparative analysis suggests the effect of pairing and collective
meandering on the energetics of the stripe formation to be secondary. The
implications of this microscopic picture of fermions bound to the 1D
antiferromagnetic ADW for the effective theories of the stripe phase in the
cuprates are discussed.
