Moessbauer absorption anomaly of gamma radiation via nuclear level anticrossing

Electromagnetically induced transparency (EIT) is a phenomenon, where the superposition of quantum state and quantum interference are utilized, and the electromagnetic waves that is ought to be resonantly absorbed transmit a material as if the material has turned transparent. This study synthesized FePSe₃ single crystal as a material for causing EIT with γ-rays, and using this material as an absorber, measured its Moessbauer spectra. In addition, this study pulverized the single crystal sample to measure Moessbauer spectra, and by realizing the appearance of six peaks, attempted the improvement of analysis accuracy by settling the values of internal magnetic field and splitting width. When the internal magnetic field is increased, energy levels of m_e = 1/2 and m_e = -3/2 overlap. In this case, the two levels not only cross, but also mix to produce new two eigenstates. It was clarified that under the temperatures in the vicinity where the levels cross, there was a possibility that the new eigenstates due to the mixing of m_e = 1/2 and m_e = -3/2 could be observed. (A.O.)