Intersublattice f-d exchange interaction in the intermetallic Laves phase compounds Y 1−tGd t(Co 1−xAl x) 2

Abstract

Systems Y 1− t ( Co 1− x Al x ) 2 with x = 0.05, 0.07, 0.085, 0.105 and 0 ≤ t ≤ 0.2 are studied to ascertain the influence of the intersublattice f-d exchange interaction on the magnetic behaviour of itinerant metamagnets Y( Co 1− x Al x ) 2. The field of the metamagnetic transition decreases when the Gd-concentration is increased for the compounds with x ≥ 0.07, and then a ferrimagnetic state is stable for more Gd-substitutions. Results obtained are explained in the molecular field approximation taking into consideration the itinerant metamagnetism of the d-electron subsystem. Intersublattice molecular field coefficient λ fd is determined from both Gd-concentration dependence on the critical field of the metamagnetic transition and values of the critical field of the rise of a non-collinear magnetic structure in high external magnetic fields. The same value of λ fd = 640 kOe/ μ B f. u. is obtained by different methods.