Kondo breakdown in multi-orbital Anderson lattices induced by destructive hybridization interference

In this paper we consider a multi-band extension to the periodic Anderson model. We use a single site DMFT(NRG) in order to study the impact of the conduction band mediated effective hopping of the correlated electrons between the correlated orbitals onto the heavy Fermi-liquid formation. Whereas the hybridization of a single impurity model with two distinct conduction bands always adds up constructively, T_{K}\propto \exp(-\mathrm{const}\, U/(\Gamma_1+\Gamma_2)) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>T</mml:mi> <mml:mi>K</mml:mi> </mml:msub> <mml:mo>∝</mml:mo> <mml:mo>exp</mml:mo> <mml:mo stretchy="false" form="prefix">(</mml:mo> <mml:mo>−</mml:mo> <mml:mstyle mathvariant="normal"> <mml:mi>c</mml:mi> <mml:mi>o</mml:mi> <mml:mi>n</mml:mi> <mml:mi>s</mml:mi> <mml:mi>t</mml:mi> </mml:mstyle> <mml:mspace width="0.167em"/> <mml:mi>U</mml:mi> <mml:mi>/</mml:mi> <mml:mo stretchy="false" form="prefix">(</mml:mo> <mml:msub> <mml:mi>Γ</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>+</mml:mo> <mml:msub> <mml:mi>Γ</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:mo stretchy="false" form="postfix">)</mml:mo> <mml:mo stretchy="false" form="postfix">)</mml:mo> </mml:mrow> </mml:math> , we show that this does not have to be the case in lattice models, where, in remarkable contrast, also an low-energy Fermi-liquid scale T_0\propto \exp(-\mathrm{const}\, U/(\Gamma_1-\Gamma_2)) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>T</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>∝</mml:mo> <mml:mo>exp</mml:mo> <mml:mo stretchy="false" form="prefix">(</mml:mo> <mml:mo>−</mml:mo> <mml:mstyle mathvariant="normal"> <mml:mi>c</mml:mi> <mml:mi>o</mml:mi> <mml:mi>n</mml:mi> <mml:mi>s</mml:mi> <mml:mi>t</mml:mi> </mml:mstyle> <mml:mspace width="0.167em"/> <mml:mi>U</mml:mi> <mml:mi>/</mml:mi> <mml:mo stretchy="false" form="prefix">(</mml:mo> <mml:msub> <mml:mi>Γ</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>−</mml:mo> <mml:msub> <mml:mi>Γ</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:mo stretchy="false" form="postfix">)</mml:mo> <mml:mo stretchy="false" form="postfix">)</mml:mo> </mml:mrow> </mml:math> can emerge due to quantum interference effects in multi-band models, where U <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>U</mml:mi> </mml:math> denotes the local Coulomb matrix element of the correlated orbitals and \Gamma_i <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msub> <mml:mi>Γ</mml:mi> <mml:mi>i</mml:mi> </mml:msub> </mml:math> the local hybridization strength of band i <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>i</mml:mi> </mml:math> . At high symmetry points, heavy Fermi-liquid formation is suppressed which is associated with a breakdown of the Kondo effect. This results in an asymptotically scale-invariant (i.e., power-law) spectrum of the correlated orbitals \propto|\omega|^{1/3} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>∝</mml:mo> <mml:mo stretchy="false" form="prefix">|</mml:mo> <mml:mi>ω</mml:mi> <mml:msup> <mml:mo stretchy="false" form="prefix">|</mml:mo> <mml:mrow> <mml:mn>1</mml:mn> <mml:mi>/</mml:mi> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> , indicating non-Fermi liquid properties of the quantum critical point, and a small Fermi surface including only the light quasi-particles. This orbital selective Mott phase demonstrates the possibility of metallic local criticality within the general framework of ordinary single site DMFT.