Charge Transfer Effect under Odd-Parity Crystalline Electric Field: Divergence of Magnetic Toroidal Fluctuation in $\beta$-YbAlB${}_4$

Abstract

A novel property of the quantum critical heavy fermion superconductor $\beta$-YbAlB${}_4$ is revealed theoretically. By analyzing the crystalline electronic field (CEF) on the basis of the hybridization picture, odd parity CEF is shown to exist because of sevenfold configuration of B atoms around Yb, which breaks the local inversion symmetry. This allows onsite admixture of 4f and 5d wavefunctions with a pure imaginary coefficient, giving rise to the magnetic toroidal (MT) degree of freedom. By constructing a realistic minimal model for $\beta$-YbAlB${}_4$, we show that onsite 4f-5d Coulomb repulsion drives charge transfer between the 4f and 5d states at Yb, which makes the MT fluctuation as well as the electric dipole fluctuation diverge simultaneously with the critical Yb-valence fluctuation at the quantum critical point of the valence transition.

arXiv comment5 pages, 3 figures

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Cited by in corpus (8)

• Unified description of electronic orderings and cross correlations by complete multipole representation
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• Magnetic Toroidal Moment under Partial Magnetic Order in Hexagonal Zigzag-Chain Compound Ce${}_3$TiBi${}_5$
• Pressure dependence of the magnetic ground state in CePtSi2
• Ultrasound Response in Quantum Critical $\beta$-YbAlB${}_4$ and $\alpha$-YbAl${}_{0.986}$Fe${}_{0.014}$B${}_4$
• Odd-Parity Crystalline Electric Field and Multipoles in Icosahedral Quasicrystal and Approximant: Magnetic Toroidal and Electric Dipoles in Ce-Based Systems
• Strong in-plane anisotropy in the electronic structure of fixed-valence $\beta$-LuAlB${}_4$
• Charge Transfer Effect under Odd-Parity Crystalline Electric Field