Magnetic interactions and phase transitions in crystals in the system Mn1−<i>t</i>Fe<i>t</i> As
Abstract
The magnetic properties of single crystals in the system Mn1−tFet As are investigated experimentally. It is established that under all variations in the external conditions (pressure, temperature, Fe concentration), an “easy surface” type of anisotropy occurs. A model is proposed for the magnetic ordering of the high-pressure phase, which has a spontaneous magnetic moment. The magnetic interactions in the isostructural alloys Mn1−t Tt As (T = V, Cr, Fe, Co, Ni), as well as in MnAs1−tPt are analyzed. It is shown that isotropic superexchange and exchange via the conduction electrons play the most important role in the formation of the observed magnetic structures, in particular, the double a-type spiral. The results obtained are used to interpret the effect of pressure and magnetic field on the magnetic behavior of the system studied.