Kondo hybridization and quantum criticality in $\beta$-YbAlB${}_4$ by laser-ARPES

Abstract

We report an angle-resolved photoemission (ARPES) study of $\beta$-YbAlB${}_4$, which is known to harbor unconventional quantum criticality (QC) without any tuning. We directly observe a quasiparticle peak (QP), emerging from hybridization, characterized by a binding energy and an onset of coherence both at about 4 meV. This value conforms with a previously observed reduced Kondo scale at about 40 K. Consistency with an earlier study of carriers in $\beta$-YbAlB${}_4$ via the Hall effect strongly suggests that this QP is responsible for the QC in $\beta$-YbAlB${}_4$. A comparison with the sister polymorph $\alpha$-YbAlB${}_4$, which is not quantum critical at ambient pressure, further supports this result. Indeed, within the limitation of our instrumental resolution, our ARPES measurements do not show tangible sign of hybridization in this locally isomorphic system, while the conduction band we observe is essentially the same as in $\beta$-YbAlB${}_4$. We therefore claim that we identified by ARPES the carriers responsible for the QC in $\beta$-YbAlB${}_4$. The observed dispersion and the underlying hybridization of this QP are discussed in the context of existing theoretical models.

arXiv comment12 pages including Supplemental Materials, with 5 figures and 3 supplemental figures

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Cited by in corpus (8)

• Effect of Anisotropic Hybridization in YbAlB${}_4$ Probed by Linear Dichroism in Core-Level Hard X-ray Photoemission Spectroscopy
• Charge Transfer Effect under Odd-Parity Crystalline Electric Field: Divergence of Magnetic Toroidal Fluctuation in $\beta$-YbAlB${}_4$
• High temperature antiferromagnetism in Yb based heavy fermion systems proximate to a Kondo insulator
• Two-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu${}_2$
• Hidden charge density wave induced shadow bands and ultrafast dynamics of CuTe investigated using time-resolved ARPES
• Quantum critical behaviour and Lifshitz transition in intermediate valence $\alpha$-YbAlB${}_4$
• Ultrasound Response in Quantum Critical $\beta$-YbAlB${}_4$ and $\alpha$-YbAl${}_{0.986}$Fe${}_{0.014}$B${}_4$
• Charge Transfer Effect under Odd-Parity Crystalline Electric Field