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High-field ESR


The transmittance geometry is suitable for relatively transparent samples (I/I0>10-6). Frequency range: 30 - 1200 GHz, Magnetic fields: 0 - ±8 T. Advantage: in addition to conventional field-sweeps, frequency sweeps and phase-shift experiments can be carried out.


transmittance geometry


Example 1:


transmittance and phase-shift
Frequency-dependent transmittance and phase-shift of La0.95Sr0.05MnO3 single crystal in zero external magnetic field. This behavior results from the (high-frequency) line of the antiferromagnetic resonance (AFMR) in La0.95Sr0.05MnO3. Symbols – experiment, lines – model calculation assuming a Lorentzian form of the line and neglecting a weak line-splitting. The interference patterns are due to the reflectance from the sample edges. The magnetic permeability (μ1+iμ2, inset) has been calculated from the transmittance and phase-shift using the Fresnel equations. The reflectance geometry is suitable for conducting samples. Frequency range: 30 - 1200 GHz, Magnetic fields: 0 - ±16 T. In this geometry a field modulation can be used to increase the sensitivity.
reflectance geometry

Example 2:


ESR signal
High-field ESR spectra of the magnetic superconductor RuSr2GdCu2O8. The line splitting at low temperatures is probably the result of the magnetic ordering at ~130 K. The superconductivity (Tc~30 K) is suppressed in high magnetic fields.


For further information contact: peter.lunkenheimer@physik.uni-augsburg.de