Ca3Ru2O7 : Interplay among degrees of freedom and the role of the exchange correlation

This is the authors' abstract. We don't add key points for this paper.

<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:msub><a:mi>Ca</a:mi><a:mn>3</a:mn></a:msub><a:msub><a:mi>Ru</a:mi><a:mn>2</a:mn></a:msub><a:msub><a:mi mathvariant="normal">O</a:mi><a:mn>7</a:mn></a:msub></a:mrow></a:math> is a fascinating material that displays physical properties governed by spin-orbit interactions and structural distortions, showing a wide range of remarkable electronic phenomena. Here, we present a density-functional-based analysis of the interplay among degrees of freedom, such as magnetism, Coulomb repulsion (Hubbard <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mi>U</c:mi></c:math>), and structural degrees of freedom, considering two exchange-correlation methods: local density approximation (LDA) and Perdew-Burke-Ernzerhof revised for solids (PBEsol). Our goal is twofold: first, to present a brief overview of the current state of the art on this compound underpinning to the last proposed theoretical models and experimental research, and second, to provide an alternative interpretation of the electronic properties compared with the previous theoretical models. Our findings show that <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msub><d:mi>Ca</d:mi><d:mn>3</d:mn></d:msub><d:msub><d:mi>Ru</d:mi><d:mn>2</d:mn></d:msub><d:msub><d:mi mathvariant="normal">O</d:mi><d:mn>7</d:mn></d:msub></d:mrow></d:math> displays several electronic states (metal, semimetal, and narrow insulator) as a function of Hubbard <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mi>U</f:mi></f:math> while it exhibits structural transition depending on the functional. We disentangle the effect of the different degrees of freedom involved, clarifying the role of exchange correlation in the observed electronic and structural transitions. Published by the American Physical Society 2024