In Silico Structural Optimization and Investigation of Bulk Lanthanum Manganite for Applications in Cancer Treatment

Lanthanum manganite is a perovskite with promising physical attributes for applications in magnetic hyperthermia cancer therapies. Through the use of first-principals electronic structure calculations, I investigate the ground-state properties of bulk rhombohedral phase lanthanum manganite in both pure and Ba doped configurations. While the hexagonal setting for this phase of the material has been previously modelled, this is the first time that the rhombohedral setting will be explored. The total magnetic moment per unit cell of 4μB per Mn-atom is found to be in agreement with the hexagonal setting. Dirac cone structures are observed in the spin-up polarized electronic bands, while an insulating gap of approximately 2.5 eV is found in the spin-down channel. 50% Ba-doped rhombohedral phase lanthanum manganite in the rhombohedral setting is modelled for the first time. It is found that additional states exist in the spin-up channel when compared to the un-doped unit cell, while a reduced band-gap of approximately 1.5 eV is observed in the spin-down channel. The total magnetic moment per doped cell is found to be 7μB, indicating a reduction in the magnetic strength for the ferromagnetic phase. This serves as an important example of the ability for rhombohedral phase lanthanum manganite to act as a basis for doped variations with tuneable properties, a critical behaviour necessary for the creation of targeted hyperthermia nano-particles. Further research involving simulating this material on the nano-scale at temperatures relevant to the human body is strongly suggested by the results of this thesis.