Zero bias anomaly in Andreev reflection spectroscopy

Joule heating effects in high-transparency Josephson junctions

“…They have been systematically investigated by Choi et al [23] in highly transparent superconductor-graphene-superconductor (SGS) Josephson junctions on silicon oxide substrate, who have made an important observation that the Joule heating power P C , at which the leads become normal, does not depend on the gate voltage controlling the junction resistance. Similar dips in dI/dV are also observed in normal metal-superconductor (NS) junctions [24,25]. Positions of the dips in the differential conductance provide information about temperature dependence of the cooling power, i.e., the heat flow out of the junction, which is important for bolometry applications.…”

“…( 15) and ( 16) agree with many experimental observations reported in the literature. Indeed, experiments in finite magnetic field [22] have shown that the critical voltage is proportional to the superconducting gap, V C ∝ (0), and the experiments with tip-shaped superconducting electrodes [24,25] demonstrated that it is proportional to the square root of the interfacial resistance R IF (V C ∝ √ R IF ). Equation ( 16) predicts that the critical power does not depend on the junction resistance in agreement with the 134513-3 12) numerically, and red dashed line represents the approximate expression (7).…”

“…In spite of their frequent observation, detailed theoretical description of the dips in dI/dV described above is still lacking. Historically, several models have been proposed in literature to explain their origin: multiple reflections of quasiparticles between the bulk of the superconducting lead and the contact area [21], suppression of superconductivity in the leads by high current density [22] and by magnetic field induced by the current [24,25]. At present, it is understood that Joule heating is the main cause of the above-gap features in junctions with the resistance exceeding that of the leads.…”

Magnetically stable zero-bias anomaly in Andreev contact to the magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$

“…2(a) and Fig. 4(a) cannot arise due to the Kondo effect, since they are symmetric and do not show a double-peak structure under the applied magnetic field 78,80,81 . Furthermore, one should point out a possibility for the impurityinduced ZBA, which was actively studied with regard to semiconductor nanowires [54][55][56][57][58][59][60] .…”

“…A number of mechanisms resulting in ZBA in mesoscopic physics can be ruled out for our experiment. This in particular concerns the Oersted field-induced ZBA, when the circular Oersted field, exceeding the critical field H c of a superconductor due to a large current density through an interface of a large area, leads to the current driven resistance peaks and ZBA 78,79 . Such a possibility can be excluded since (i) ZBAs caused by the Oersted field are usually sensitive to an external magnetic field 78 ; (ii) ZBAs caused by the Oersted field exist almost till the superconductor's T c 78 , in contrast to the temperature dependence in Fig.…”