Gate dependence of upper critical field in superconducting (110) LaAlO3/SrTiO3 interface

The fundamental parameters of the superconducting state such as coherence length and pairing strength are essential for understanding the nature of superconductivity. These parameters can be estimated by measuring critical parameters such as upper critical field, H c2 . In this work, H c2 of a superconducting (110) LaAlO 3 /SrTiO 3 interface is determined through magnetoresistive measurements as a function of the gate voltage, V G . When V G increases, the critical temperature has a dome-like shape, while H c2 monotonically decreases. This relationship of independence between the variation of T c and of H c2 suggests that the Cooper pairing potential is stronger in the underdoped region and the coherence length increases with the increase of V G . The result is as for high temperature superconducting cuprates and it is different than for conventional low temperature superconductors.