Fabrication of BaKFeAs Intergrain Nanobridges by Using a Focused Ion Beam

다국어 초록 (Multilingual Abstract)

We have studied the fabrication and the transport properties of Ba_0.6K_0.4Fe₂As₂ intergrain nanobridges patterned by using a focused ion beam (FIB). Prior to FIB etching, 8-μm-wide bridges were prepatterned from Ba_0.6K_0.4Fe₂As₂ films by using argon ion milling with a photoresist mask. The lowest-possible beam current of 1.5 pA was used for the FIB nanobridge pattern to minimize the etching damage to the bridge. The nanobridge contained a single grain boundary, and the nominal dimensions were 200 nm in width and 100 nm in length. We have also studied current-voltage (<i>I-V</i>) characteristics, the temperature-dependent critical current (<i>I_c</i>), and the normal-state resistance (<i>R_N</i>). The transport measurements of the nanobridge showed a strong-coupling nature with a high critical current density of 1.25 × 10⁶ A/cm² at 4.2 K, which is comparable to the intragrain value. The nanobridge showed the onset of a resistive transition at 37 K and zero resistance at 27 K. Measured <i>I-V</i> curves were dominated mainly by Josephson coupling, showing resistivelyshunted-junction (RSJ) behaviors with multiple transitions at low temperatures. The temperature dependence of the critical current was <i>I_c</i> ∼ (1 − <i>T</i>/<i>T_c</i>)^1.0.

참고문헌 (Reference)

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