Combined THz and Pulsed EPR studies on a Yb(III) Single Ion Magnet

Recently, the development of single molecule magnets has shifted rapidly away from the use of transition metals in favor of lanthanides due to their large single ion anisotropy. This is a direct consequence of the relatively strong spin-orbit coupling inherent to lanthanides, which, in the presence of the appropriate crystal field, gives rise to well separated spin-orbit projected states that can permit slow relaxation of the magnetization. The motivation for studying such systems presumes that the so-called Orbach process provides the primary pathway through which the magnetization relaxes. However, previous studies on Yb(trensal) (1) have shown that simply having a large zero field energy barrier is not a sufficient criterion to achieve a high blocking temperature. In doing so, it was demonstrated that 1 also has the additional potential for use as a molecular spin qubit. To further investigate these properties in 1, we employ both Fourier Transform Far Infrared spectroscopy and pulsed EPR measurements to: i) characterize the zero field splitting associated with the crystal field and ii) probe the interactions that limit both spin-lattice and spin-spin relaxation by measuring the dependence on temperature and magnetic field.