Influence of nitrogen stoichiometry and the role of Sm <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>5</mml:mn> <mml:mi>d</mml:mi> </mml:math> states in SmN thin films

Abstract

We report a comprehensive study of the synthesis of epitaxial SmN thin films on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msub> <a:mi>LaAlO</a:mi> <a:mn>3</a:mn> </a:msub> </a:math> (100) by molecular beam epitaxy under slow-growth conditions. By carefully tuning the substrate temperature and the molecular nitrogen partial pressure, we are able to control the nitrogen content of our samples and produce near-stoichiometric, well-ordered SmN thin films. The influence of nitrogen defects on the samarium ion valence and the electronic structure is investigated by x-ray absorption and photoelectron spectroscopy, suggesting that the empty Sm <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mn>5</b:mn> <b:mi>d</b:mi> </b:math> states may act as a charge reservoir stabilizing the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:mn>4</c:mn> <c:msup> <c:mi>f</c:mi> <c:mn>5</c:mn> </c:msup> </c:mrow> </c:math> configuration in the nitrogen-deficient compound. The spectra also reveal a significant hybridization of the Sm <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mn>4</d:mn> <d:mi>f</d:mi> </d:math> and N <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mn>2</e:mn> <e:mi>p</e:mi> </e:math> states. Published by the American Physical Society 2024