Multiple magnetic phase transitions with different universality classes in bilayer La_{1.4}Sr_{1.6}Mn_{2}O_7 manganite

Abstract

Here, we report three magnetic transitions at 101 K (T_{C1}), 246 K (T_{C2}) and 295 K (T_{C3}) in bilayer La_{1.4}Sr_{1.6}Mn_{2}O_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}, T_{C2} and T_{C3} 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},(2) 2D Heisenberg canted antiferromagnetic (CAFM-I) and FM clusters in temperature range T_{C1} < T < T_{C2}, (3) 2D Heisenberg CAFM-II and FM clusters with non magnetically interacting planes in temperature range T_{C2} < T < T_{C3} and (4) paramagnetic for T > T_{C3}.