Multiple magnetic phase transitions with different universality classes in bilayer La $$_{1.4}$$ 1.4 Sr $$_{1.6}$$ 1.6 Mn $$_{2}$$ 2 O $$_7$$ 7 manganite

Abstract

Abstract Here, we report three magnetic transitions at 101 K (T $$_{C1}$$ C 1 ), 246 K (T $$_{C2}$$ C 2 ) and 295 K (T $$_{C3}$$ C 3 ) in bilayer La $$_{1.4}$$ 1.4 Sr $$_{1.6}$$ 1.6 Mn $$_{2}$$ 2 O $$_7$$ 7 . The second order phase transitions have been identified at these transition points with the help of change in entropy analysis and modified Arrott plots (MAPs). The critical behavior around T $$_{C1}$$ C 1 , T $$_{C2}$$ C 2 and T $$_{C3}$$ C 3 have been studied by MAPs and Kouvel–Fisher method. Based on these analyses four magnetic phases are: (1) 2D Ising ferromagnetic (FM) below T $$_{C1}$$ C 1 ,(2) 2D Heisenberg canted antiferromagnetic (CAFM-I) and FM clusters in temperature range T $$_{C1}$$ C 1 T $$_{C3}$$ C 3 .