Dynamics of the response to microwave radiation in YBa2CU3O7-x hot-electron bolometer mixers

We present a systematic study of the intermediate frequency (IF) bandwidth of hot-electron bolometer mixers made from YBa2Cu3O7-x high-temperature sup erconductive thin films fabricated on substrates with high thermal conducti vity (MgO and sapphire). At a local oscillator frequency of 100 GHz, a stro ng dependence of the IF bandwidth on the bias point and temperature has bee n experimentally found. Moreover, an unexpected IF bandwidth variation has been detected in a broad range of operating frequencies (1-480 GHz). Beside s conventional bolometric mixing mechanisms associated with thermalization of electrons and phonons, the contribution of direct interaction between ra diation and magnetic vortices in the YBa2Cu3O7-x film may be responsible fo r the observed effects. (C) 2001 American Institute of Physics.