Single-crystal Growth of Underdoped Bi-2223

To investigate the origin of the enhanced Tc (≈ 110 K) of the trilayer cuprate superconductor Bi2Sr2Ca2Cu3O10+δ (Bi-2223), its underdoped single crystals are a critical requirement. Here, we demonstrate the first successful in-plane resistivity measurements of heavily underdoped Bi-2223 (zero-resistivity temperatures ≈ 20∼35 K). Detailed crystal growth methods, the annealing process, as well as X-ray diffraction (XRD) and magnetic susceptibility measurement results are also reported.