  Structural defects are important for both solid-state chemistry and physics,
as they can have a significant impact on chemical stability and physical
properties. Here, we identify a vacancyinduced pseudo-gap formation in
antiferromagnetic Cr$_{0.86}$ZnSb. Cr$_{1-x}$ZnSb alloys were studied combining
efforts of density functional theory (DFT) calculations and experimental
methods to elucidate the effect of vacancies. Detailed analyses (X-ray powder
and single crystal diffraction, transmission and secondary scanning electron
microscopy) of Cr$_{1-x}$ZnSb, $0<x<0.20$, prompts Cr$_{0.86}$ZnSb as the only
stable compound, crystallizing with the MnAlGe-type structure. From DFT
calculations, an antiferromagnetic spin configuration of Cr local magnetic
moments was found to be favorable for both, the perfectly stoichiometric
compound CrZnSb, as well as for Cr$_{0.875}$ZnSb. Magnetic order is observed
experimentally for Cr$_{0.86}$ZnSb by temperature- and field-dependent
magnetization measurements, revealing a magnetic phase transition near 220 K,
which is corroborated by zero-field muon spin relaxation studies.
Thermoelectric transport properties exhibit distinct maxima in the
temperature-dependent Seebeck coefficient and electrical resistivity at around
190 K. Analyzing the measured data on the basis of a triple parabolic band
model and DFT simulations, their characteristic features are traced back to a
pseudo-gap in the electronic structure arising from a particular vacancy
arrangement.
