## 3 Results  
The \(I\)-\(V\) curves of fabricated bicrystal YBa\({}_{2}\)Cu\({}_{3}\)O\({}_{7-x}\) junctions were measured in the current-bias mode using a four-probe technique. The differential resistances d\(V\)/d\(I\) have been measured by a current modulation technique with a lock-in amplifier, and differential conductances d\(I\)/d\(V\)= (d\(V\)/d\(I\))\({}^{-1}\) have been calculated from the measured d\(V\)/d\(I\). With current modulation not exceeding the thermal currents \(I_{\rm th}\) = 0.4 \(\mu\)A at \(T\) = 5 K, it was possible to reach the accuracy \(\delta\)(d\(I\)/d\(V\))/d\(I\)/d\(V\) not worse than 1% at the amplifier bandwidth of 1 Hz. The voltage (and frequency) accuracy is finite due to voltage fluctuations, and the spectral resolution is due to the broadening of the Josephson linewidth by voltage fluctuations, correspondingly. The frequency accuracy of 1 GHz and spectral resolution of around 10 GHz are the typical values for JJ with \(R_{n}\) around 1 \(\Omega\)[17]. Figure 3 shows the \(I\)-\(V\) curve and the dependence of the differential conductance d\(I\)/d\(V\) on the voltage \(V\) for typical bicrystal YBa\({}_{2}\)Cu\({}_{3}\)O\({}_{7-x}\) junctions fabricated from two \(c\)-axis thin films (a) and two films with mutually tilted \(c\)-axes (b). The data in Figure 3a belong to the JJyd007201 on a 2 \(\times\) 14\({}^{\circ}\) bicrystal NdGaO\({}_{3}\) substrate at \(T\) = 5 K. The data in Figure 3b correspond to the JJyd502021 on a 2 \(\times\) 12\({}^{\circ}\) bicrystal SrTiO\({}_{3}\) substrate at \(T\) = 10 K.  
The \(I\)-\(V\) curve in Figure 3a is close to that in the RSJ model, with the resistance \(R_{n}\) = 1.2 \(\Omega\) and the characteristic voltage \(I_{c}R_{n}\) = 3 mV (see the dashed line). The dependence of d\(I\)/d\(V\) vs. the voltage \(V\) for this sample shows no localized features and no noticeable deviations from the RSJ model. However, the \(I\)-\(V\) curve and the dependence of d\(I\)/d\(V\) vs. the voltage \(V\) for the JJ with mutually tilted \(c\)-axes (Figure 3b) demonstrate that there are noticeable deviations from the RSJ model, localized at voltages around 9.4 mV, as well as weaker deviations at voltages around 11.8 mV and 7.4 mV. There are also less intensive features at lower voltages. The noted features on the first derivatives of the \(I\)-\(V\) curves have an odd-symmetric form, which indicates  
Figure 2: An example of the modification of the \(I\)–\(V\) curve of the Josephson junction described by the RSJ model (**top** panel) by a hypothetical external admittance containing two weak Lorentz lines at normalized frequencies h\(f\)/2 el\(I_{c}R_{n}\) = 0.75 and 2 (**bottom** panel) in the real part. The spectral dependence of the external conductivity \(Y_{e}\)(\(f\)) is related to the difference \(\Delta I(V)\) between the modified \(I_{e}\) (solid blue) and autonomous \(I_{0}\) (dashed grey) \(I\)–\(V\) curves according to Equation (2). A thick green curve is the first derivative d\(I\)/d\(V\) vs. voltage \(V\) of the junction under external shunting, while a dashed grey curve—d\(I_{0}\)/d\(V\) for the autonomous junction. the localized dips in the \(I\)-\(V\) curve. Indeed, on the \(I\)-\(V\) curve in Figure 3, one can distinguish a dip at voltages of about 9.4 mV. The \(I\)-\(V\) curve in Figure 3b has been fitted to the RS) model with the resistance \(R_{n}\) = 1.3 \(\Omega\) and the characteristic voltage \(l_{c}R_{n}\) = 6 mV (see the dashed line). The features on the \(I\)-\(V\) curves of YBa\({}_{2}\)Cu\({}_{3}\)O\({}_{7-x}\) bicrystal JJs with mutually tilted \(c\)-axes are reproducible in their positions on the voltage axis when fabricating JJs of various widths on various substrates (SrTiO\({}_{3}\) or NdGaO\({}_{3}\)), and also at different temperatures. Figure 4 shows the dependences of the differential conductances for two JJs with different widths (a) and for one JJ at two temperatures (b).