Effects of magnetic fields on the coherent THz emission from mesas of single crystal Bi2Sr2CaCu2O8+δ

We have measured the magnetic field effect of THz radiation emitted from a mesa structure fabricated from high-quality high-transition temperature (Tc) superconductor single crystalline Bi2Sr2CaCu2O8+δ using a newly developed measurement system in magnetic fields up to 6 T. The results show that the THz radiation was strongly suppressed in magnetic fields with a considerable anisotropy: about 20 Oe magnetic field is sufficient for the total suppression of the THz radiation for the field being parallel to the c-axis, while for the field being parallel to the ab-plane the radiation has first a slight hump at about 50 Oe, then has a sudden drop at about 150 Oe, and shows a step-wise structure between about 200 and 300 Oe before the intensity diminishes completely below the detection sensitivity limit at about 450 Oe. These characteristic features are discussed in comparison with recent theoretical works.