Interface density driven metal-to-insulator transition in nickelate based heterostructures

Heterostructures made of alternating metallic layers of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:msub> <a:mi>Nd</a:mi> <a:mrow> <a:mn>0.7</a:mn> </a:mrow> </a:msub> <a:msub> <a:mi>La</a:mi> <a:mrow> <a:mn>0.3</a:mn> </a:mrow> </a:msub> <a:msub> <a:mi>NiO</a:mi> <a:mn>3</a:mn> </a:msub> </a:mrow> </a:math> and layers displaying a metal-to-insulator transition (such as <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:msub> <b:mi>SmNiO</b:mi> <b:mn>3</b:mn> </b:msub> </b:math> ) have been grown varying the period of the superlattices on top of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:msub> <c:mi>LaAlO</c:mi> <c:mn>3</c:mn> </c:msub> </c:math> substrates. Exploiting the phase boundary cost found between metallic and insulating phases of nickelates, it is shown that a metallic layer can be turned into an insulating one by means of heterostructuring in an intermediate thickness regime in which the single layers retain their metallic behavior.