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 (TC1), 246 K (TC2) and 295 K (TC3) in bilayer La1.4Sr1.6Mn2O7. 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 TC1, TC2 and TC3 have been studied by MAPs and Kouvel–Fisher method. Based on these analyses four magnetic phases are: (1) 2D Ising ferromagnetic (FM) below TC1,(2) 2D Heisenberg canted antiferromagnetic (CAFM-I) and FM clusters in temperature range TC1 < T < TC2, (3) 2D Heisenberg CAFM-II and FM clusters with non magnetically interacting planes in temperature range TC2 < T < TC3 and (4) paramagnetic for T > TC3.