High magnetic field response of superconductivity dome in quantum artificial high − T C superlattices with variable geometry

It is known that cuprate artificial high- <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msub> <a:mi>T</a:mi> <a:mi>C</a:mi> </a:msub> </a:math> superlattices (AHTS) with period <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mi>d</b:mi> </b:math> , composed of quantum wells confining interface space charge in stoichiometric Mott insulator layers ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:mi>S</c:mi> </c:mrow> </c:math> ), with thickness <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mi>L</d:mi> </d:mrow> </d:math> , at the interface with overdoped normal metallic cuprate layers ( <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:mi>N</e:mi> </e:mrow> </e:math> ) show a superconducting dome by tuning the geometric <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:mrow> <f:mi>L</f:mi> </f:mrow> </f:math> over <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mi>d</g:mi> </g:math> ratio of the SNSN superlattice with the top predicted by quantum material design engineering quantum size effects. Here we report high-field magnetotransport measurements up to 41 Tesla of AHTS across the entire superconducting dome. The results show the universal upward-concave behavior of the temperature-dependent upper critical magnetic field in low- <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"> <h:msub> <h:mi>T</h:mi> <h:mi>C</h:mi> </h:msub> </h:math> samples at the rising edge and drop edge of the dome, providing strong evidence consistent with two-band superconductivity in agreement with multigap theory used for quantum design of the SNSN superlattices. The measured superconducting coherence length demonstrates that atomic-scale engineering controls not only the critical temperature but also the intrinsic pair size at Fano-Feshbach resonances physics paving the way toward next-generation quantum devices and shedding light on unconventional superconductivity.