Terahertz emission from intrinsic Josephson junctions in trilayer cuprate superconductor Bi₂Sr₂Ca₂Cu₃O_10+<i>δ</i>

Abstract This study presents the first observation of a continuous electromagnetic terahertz wave emission from mesoscopic mesas of the trilayer high- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> </mml:msub> <mml:mspace width="1em"/> </mml:math> superconductor, Bi 2 Sr 2 Ca 2 Cu 3 O 10+ δ (Bi-2223), a putative Josephson plasma emitter utilizing intrinsic Josephson junctions. Two types of Bi-2223 crystals, optimally doped and underdoped, were prepared via thermal annealing under controlled partial oxygen pressures, and their electrical and emission characteristics were compared. A weak, but detectable terahertz emission was observed from the underdoped Bi-2223 mesas, whereas no radiation was observed from the optimally doped ones. We associate the low terahertz emission output with the weak capacitive coupling between the intrinsic junctions in the trilayer system.