Gate-tunability of the superconducting state at the $EuO/KTaO_3 (111)$ interface

TL;DR

This study explores the superconducting properties of EuO/KTaO_3 (111) interfaces, demonstrating gate-tunable superconductivity with a maximum T_C of about 2 K and revealing an inverse relationship between critical magnetic field and T_C.

Contribution

It provides new insights into gate-tunable superconductivity at EuO/KTaO_3 interfaces and highlights the relationship between carrier density, magnetic field, and superconducting properties.

Findings

Maximum T_C of ~2 K at specific carrier density

Critical current density can be tuned by back gate voltage

Upper critical magnetic field shows opposite trend to T_C in underdoped region

Abstract

The recent discovery of superconducting interfaces in the $KTaO_3 (111)$-based heterostructures is intriguing, since a much higher superconducting critical temperature (TC ~ 2 K) is achieved compared to that in the $SrTiO_3$ heterostructures (~ 300 mK). In this paper, we report the superconducting properties of $EuO/KTaO_3 (111)$ interface as a function of the interface carrier density ($n_s$). The maximum T_C is observed to be ~ 2 K at $n_s$ ~ $1\times10^{14}$ cm-2. In addition, we show that the critical current density and the upper critical magnetic field can be effectively tuned by the back gate voltage. Interestingly, the gate dependence of the upper critical magnetic field exhibits a trend opposite to that of TC in the underdoped region, suggesting a relatively larger Cooper pairing potential.