Intrinsic Josephson properties in (Hg, Re)Ba₂Ca₃Cu₄O_10+δ single crystals

We have investigated the I-V characteristics of intrinsic Josephson junctions (IJJs) in (Hg, Re)Ba₂Ca₃Cu₄O_10+δ [Hg(Re)1234]. Two types of inline junctions with different dimensions were fabricated using a focused Ga⁺ ion beam from Hg(Re)1234 single crystals grown by the flux method. In the I-V curves of the IJJs, multiple-branches with hysteresis structure similar to those of other HTS IJJs were successfully observed above 80 K. The IJJs with dimension of 1.2 x 0.65 μm² showed almost step by step switching, while the other with larger size showed uniform-stack switching, which indicated that the switching dynamics in the IJJs were affected by the coupling between junctions. The critical current density, J_c, of both IJJs were high ∼320 kA/cm² at 4.2 K due to its high T_c and relatively low anisotropy parameter γ=(m_c*/m_ab*)^1/2∼25