טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentLeviant Tom
SubjectEnergy Bursts from the Fe8 Molecular Magnet during Quantum
Tunneling of Magnetization Process
DepartmentDepartment of Physics
Supervisor Professor Amit Keren
Full Thesis textFull thesis text - English Version


Abstract

Single molecule magnets (SMM) have been widely investigated as model compounds for quantum tunneling of magnetization. In the Fe8 molecular magnet tunneling can occur from a meta-stable state to an excited state followed by a transition to the ground state. This transition is accompanied by an energy release of 115.6 GHz. Previous work done by Oren Shafir and Amit Keren showed a jump in the temperature of a thermometer placed far from the sample, every time a tunneling event took place. The first objective of this research was to measure whether this energy is released in the form of thermal or electromagnetic energy. Contrary to a previous publication we find no evidence for the release of electromagnetic radiation. However, under some conditions this release of heat causes magnetization reversal in the form of a deflagration. The deflagration ignites by tunneling and its front velocity is of the order of 1 m/sec. This velocity is sensitive to field gradients and sweep rates. In addition, the propagation velocity of a heat pulse through the sample was measured. These measurements are discussed in the context of deflagration theory.