Chromium analogues of Iron-based superconductors

Abstract

We theoretically investigate the $d^4$ (Cr${}^{2+}$) compound BaCr${}_2$As${}_2$ and show that, despite non-negligible differences in the electronic structure, its many-body physics mirrors that of BaFe${}_2$As${}_2$, which has instead a $d^6$ (Fe${}^{2+}$) configuration. This reflects a symmetry of the electron correlation effects around the half-filled $d^5$ Mott insulating state. The experimentally known metallic antiferromagnetic phase is correctly modeled by dynamical mean-field theory, and for realistic values of the interaction it shows a moderate mass enhancement of order $\sim$2. This value decreases if the ordered moment grows as a result of a stronger interaction. The antiferromagnetic phase diagram for this $d^4$ shows similarities with that calculated for the $d^6$ systems. Correspondingly, in the paramagnetic phase the influence of the half-filled Mott insulator shows up as a crossover from a weakly correlated to an orbitally differentiated "Hund's metal" phase which reflects an analogous phenomenon in $d^6$ iron compounds including a strong enhancement of the compressibility in a zone just inside the frontier between the normal and the Hund's metal. The experimental evidence and our theoretical description place BaCr${}_2$As${}_2$ at interaction strength slightly below the crossover which implies that negative pressures and/or electron doping (e.g. Cr $\to$ Mn,Fe or Ba $\to$ Sc,Y,La) might strongly enhance the compressibility, thereby possibly inducing a pairing instability in this non-superconducting compound.

arXiv comment8 pages, 8 figures

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Cited by in corpus (19)

• Role of the orbital degree of freedom in iron-based superconductors
• Dynamical correlations and order in magic-angle twisted bilayer graphene
• Spin-orbit coupling effects on the electronic properties of the pressure-induced superconductor CrAs
• Observation of a remarkable reduction of correlation effects in BaCr2As2 by ARPES
• A minimal tight-binding model for the quasi-one-dimensional superconductor K2Cr3As3
• Hund's metal crossover and superconductivity in the 111 family of iron-based superconductors
• Enhancement of charge instabilities in Hund's metals by the breaking of rotational symmetry
• Is BaCr${}_2$As${}_2$ symmetrical to BaFe${}_2$As${}_2$ with respect to half $3d$ shell filling?
• Neutron diffraction study on magnetic structures and transitions in Sr2Cr3As2O2
• Slave-spin mean field for broken-symmetry states: Néel antiferromagnetism and its phase separation in multi-orbital Hubbard models
• Orbital-selective bad metals due to Hund's rule and orbital anisotropy: a finite-temperature slave-spin treatment of the two-band Hubbard model
• Absence of superconductivity in electron-doped chromium pnictides ThCrAsN${}_{1-x}$O${}_x$
• Nematic fluctuations in the non-superconducting iron pnictide BaFe${}_{1.9-x}$Ni${}_{0.1}$Cr${}_x$As${}_2$
• Magnetic competition in iron-based germanide and silicide superconductors
• Itinerant G-type antiferromagnet SrCr2As2 studied by magnetization, heat capacity, electrical resistivity, and NMR measurements
• Dimensionality of the superconductivity in the transition metal pnictide WP
• Enhanced Itinerant Ferromagnetism in Hole-doped Transition Metal Oxides: Beyond the Canonical Double Exchange Mechanism
• PhD Thesis: Electronic correlations in multiorbital systems
• Doping-dependent orbital magnetism in Chromium pnictides