First Principles calculation High Spin to Low Spin transition in the SrMnO3 and the CaMnO3 compound
الموضوعات : International Journal of Heterocyclic ChemistryNarges Saki 1 , Azadeh Aezami 2
1 - Departments of Physics, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
2 - Departments of Physics, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
الکلمات المفتاحية: High Spin, Low Spin, SrMnO3, CaMnO3, Enthalpy,
ملخص المقالة :
In this research, structural, electronic, magnetic, and electrical properties of SrMnO3 and CaMnO3 have been investigated using calculations based on density-functional theory from scratch and Quantum-Espresso calculation code. The Hubbard parameter has been calculated for the Mn atom using a linear response approach and LDA+U approximation for both compounds. This parameter is 3.5 eV for CaMnO3 and it is 3.1 eV for SrMnO3. The calculations showed that even though both compounds are insulator and G-type antiferromagnetic materials. Both samples have a cubic perovskite structure in which the Mn atom is located at the center of an octagon surrounded by oxygen atoms, and the vertices of a cube are the place for Sr and Ca atoms. The effect of pressure on these two compounds has been studied from %5 to %20 in tensile pressure (TP) and compressive pressure (CP) directions along the z-axis. The transition from High Spin (HS) to Low Spin (LS) of both compounds has been searched through the results of enthalpy calculations in terms of pressure. Results reveal that both materials are in stable HS and LS states in pressures higher and lower than -10 GPa and -20 GPa, respectively. Moreover, the magnetic moment of CaMnO3 in the pressure of -20.51 GPa decreases from 3.41µB in a stable HS state to 1.44 µB in an LS state, and that of SrMnO3 in the pressure of -26.87 GPa declines from 4.37 µB in HS state to 1.55 µB in LS state.
