Nearest-neighbor Ising antiferromagnet in a magnetic field—the body-centered-cubic lattice

The results of a Monte Carlo study of a nearest-neighbor Ising antiferromagnet in an external magnetic field are reported. The effect of the presence of the field on the order-disorder transition is discussed, and the alternating long-range order, staggered susceptibility, ordinary susceptibility, and specific heat as functions of temperature for several fields are presented. For small fields, the calculation is consistent with the results of series expansions, but near the critical field it disagrees with the series extrapolations, and supports qualitatively the prediction of molecular-field approximations, namely, that there can be two transitions provided that the field is slightly larger than the $T=0\mathrm{}$ critical value.