Evidence of a critical Mn-Mn distance for the onset of ferromagnetism in NiAs type compounds

Abstract

Recently, the technique of spin wave resonance has been used to measure the exchange coupling constants as a function of composition in several solid solutions of MnSb. From an examination of the results we show that in those alloys in which the linear chains of magnetic atoms are not disturbed, the exchange coupling constants become positive leading to ferromagnetic coupling when the distance between Mn atoms becomes equal to 2.83 Å or more. This experimental value of the Mn-Mn distance for the onset of ferromagnetism is equal to the critical distance derived by Forrer after examining a large number of materials which owe their ferromagnetism predominantly to the direct exchange interaction. © 1984.