Sharp steps in magnetization, magnetoresistance, and magnetostriction in Pr0.6Sr0.4Co1-yGayO3

Abstract

We report the magnetization, magnetoresistance, and magnetostriction in polycrystalline Pr0.6Sr0.4Co1-yGayO3 (y = 0.0-0.3) samples. Upon substitution of the non-magnetic Ga3+ cation for Co3+, the low temperature ground state transforms from a ferromagnetic metal for y = 0 to a cluster glass type semiconductor for y ≥ 0.2. The field-dependent magnetization, magnetoresistance, and magnetostriction for y ≥ 0.2 show reversible abrupt steps for both positive and negative magnetic fields at T ≤ 3 K, whereas all these quantities vary smoothly with the magnetic field above 4 K. Such steps in all three distinct physical quantities were never reported earlier in perovskite cobaltites, and they differ from observations made in manganites and intermetallic alloys. It is suggested that field-induced avalanche flipping of ferromagnetic clusters is the origin of observed steps in all these three quantities.