Terahertz (THz) radiation characteristics have been investigated for voltage-biased photoswitching devices (PSDs) coupled with dipole antennas made on magnetoresistive thin films. Even under a fixed illumination of femtosecond laser pulses with a power of , we find the high electric strength in PSDs made on thin films in the charge-ordered (CO) state at . THz radiation linearly enhances with an increase of the biased electric field up to without any change of the waveform of the radiated THz pulse. On the other hand, the static time-averaged photoconductance is nearly constant below but deviates from it above . Such behavior can be ascribed to an increase in the change of the fraction of photogenerated metallic patches within the CO insulating phase. Therefore our findings show that not only but also other manganites having a CO state above room temperature may act as efficient THz radiation sources.
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