Bridging the "THz gap" - ESR spectroscopy in pulsed magnetic fields - February 19, 2008
News from the Forschungszentrum Dresden-Rossendorf (FZD)
Electron spin resonance (ESR) provides a powerful means for investigating elementary excitation spectra in magnetic substances. A world-wide unmatched setup at the Dresden High-Magnetic Field Laboratory allows for a broad range of ESR applications in condensed matter, material sciences, and chemistry. The new high-field ESR setup is open for users.
Recently, at the Dresden High Magnetic Field Laboratory (HLD) a new setup allowing us to conduct ESR experiments in the THz frequency range in pulsed magnetic fields up to 70 T and beyond has been completed. As radiation source the new spectrometer utilizes the intensive (with average power up to several Watts) radiation in the wavelength range of 4 - 230 µm (~ 1.3 - 70 THz) of a nearby free-electron laser. Recently, this unique setup has been successfully tested.
Scientists who participated in the experiment:
Dr. Sergei Zvyagin, Mike Ozerov, Dr. Erik Cizmar, Dr. Artem Pronin, Dr. Yurii Skourski, Uwe Helbig.
The (6MAP)CuCl3 sample was kindly provided by Dr. Chris Landee and Dr. Mark Turnbull (Clark University, Worcester, MA, USA).
The figure shows the ESR spectrum obtained on the S = 1/2 quantum magnet (6MAP)CuCl3 in fields up to 52 Tesla at a wavelength of 228.6 µm (which approximately corresponds to a frequency of 1.3 THz). The resonances appear at a field of 44 Tesla. Applying the radiation of tunable backward wave oscillators (BWO) and Gunn-diodes permits us to extend the frequency range of the spectrometer down to 30 GHz.
Prof. Joachim Wosnitza
Director, Dresden High-Magnetic Field Laboratory
Forschungszentrum Dresden-Rossendorf (FZD)
Phone: ++49 351 260 - 3524