Multifrequency Pulsed EPR in the 120-400 GHz Range

At high fields and low temperatures both the electron spin lattice relaxation time (T₁) and spin-spin Relaxation time (T₂) can change dramatically with respect to those at lower fields. Relaxation in spin systems is of crucial interest with respect to various possible applications like quantum information processing, information storage, spintronics, and dynamic nuclear polarization (DNP). High frequencies and fields in combination with low temperatures polarize the electron spins, and allow for considerably longer spin memory times at high fields and frequencies as compared to X-band[1] for more concentrated spin systems. On the other hand, high frequencies lead to a significantly increased contribution from direct single phonon processes in the spin-lattice relaxation, and at low temperatures T₁ can be a few orders of magnitude shorter at fields of the order of 10T with respect to the spin lattice relaxation times at typical X-band frequencies.

At the National High Magnetic Field Laboratory, users have the opportunity to explore spin-relaxation at a range of frequencies and fields. Here we provide an overview and description of the spectrometers available, and discuss results of frequency dependent spin-lattice relaxation measurements in a variety of spin systems.