Abstract
The tri-layer La_{3-3x}Sr_{1+3x}Mn_{3}O_{10} manganites of Ruddlesden–Popper (RP) series are naturally arranged layered structure with alternate stacking of ω-MnO_2 (ω = 3) planes and rock-salt type block layers (La, Sr)_2O_2 along c-axis. The dimensionality of the RP series manganites depends on the number of perovskite layers and significantly affects the magnetic and transport properties of the system. Generally, when a ferromagnetic material undergoes a magnetic phase transition from ferromagnetic to paramagnetic state, the magnetic moment of the system becomes zero above the transition temperature (T _{C} ). However, the tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} shows non-zero magnetic moment above T _{C} and also another transition at higher temperature T ^{*} approx 263 K. The non-zero magnetization above T _{C} emphasizes that the phase transition in tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} not a ferromagnetic to paramagnetic state. We show here the non-zero magnetic moment above T _{C} is due to the quasi-two-dimensional nature of the tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} manganite. The scaling of the magnetic entropy change confirms the second-order phase transition and the critical behavior of phase transition has been studied around T_C to understand the low dimensional magnetism in tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10}. We have obtained the critical exponents for tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10}, which belong to the short-range two-dimensional (2D)-Ising universality class. The low dimensional magnetism in tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} manganite is also explained with the help of renormalization group theoretical approach for short-range 2D-Ising systems. It has been shown that the layered structure of tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} results in three different types of interactions intra-planer ( J_{ab} ), intra-tri-layer ( J_{c} ) and inter-tri-layer ( J' ) such that J_{ab}> J_{c}>> J' and competition among these give rise to the canted antiferromagnetic spin structure above T _{C} . Based on the similar magnetic interaction in bi-layer manganite, we propose that the tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} should be able to host the skyrmion below T _{C} due to its strong anisotropy and layered structure.
Highlights
When a ferromagnetic material undergoes a magnetic phase transition from ferromagnetic to paramagnetic state, the magnetic moment of the system becomes zero above the transition temperature (TC )
The study of tri-layer La3−3xSr1+3xMn3O10 manganite is important due to the following issues: (i) the magnetic and transport properties are not at all explored rigorously, (ii) the exchange mechanism responsible for the spin-spin interaction for FM is not known and (iii) recently observed skyrmionic-bubbles in m anganites[26,27,28,29] indicates that the tri-layer La3−3xSr1+3xMn3O10 may be a potential candidate for the skyrmion host material. These issues emphasize that a thorough magnetic analysis of the tri-layer La3−3xSr1+3xMn3O10 is required to establish the basic understanding of the magnetism and the exchange interaction involved in the tri-layer manganite
We have examined the remaining 3D and 2D models, but they cannot describe the experimental results obtained for TL-LSMO-0.3
Summary
When a ferromagnetic material undergoes a magnetic phase transition from ferromagnetic to paramagnetic state, the magnetic moment of the system becomes zero above the transition temperature (TC ). Careful synthesis of tri-layer La3−3x Sr1+3xMn3O10 manganite is required to get a high-quality sample without impurity As it stands presently, the study of tri-layer La3−3xSr1+3xMn3O10 manganite is important due to the following issues: (i) the magnetic and transport properties are not at all explored rigorously, (ii) the exchange mechanism responsible for the spin-spin interaction for FM is not known and (iii) recently observed skyrmionic-bubbles in m anganites[26,27,28,29] indicates that the tri-layer La3−3xSr1+3xMn3O10 may be a potential candidate for the skyrmion host material. In order to investigate the exchange mechanism responsible for the spin-spin interaction, a detailed critical analysis of the second-order phase transition has been carried out
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