The origin of intrinsic quantum criticality in the heavy-fermion superconductor β-YbAlB4 has been attributed to strong Yb valence fluctuations and its peculiar crystal structure. Here, we assess these contributions individually by studying the isostructural but fixed-valence compound β-LuAlB4. Quantum oscillation measurements and DFT calculations reveal a Fermi surface markedly different from that of β-YbAlB4, consistent with a `large' Fermi surface there. We also find an unexpected in-plane anisotropy of the electronic structure, in contrast to the isotropic Kondo hybridization in β-YbAlB4.
@article{arxiv.2003.14113,
title = {Strong in-plane anisotropy in the electronic structure of fixed-valence $\beta$-LuAlB$_4$},
author = {Pascal Reiss and Jordan Baglo and Hong'En Tan and Xiaoye Chen and Sven Friedemann and Kentaro Kuga and F. Malte Grosche and Satoru Nakatsuji and Michael Sutherland},
journal= {arXiv preprint arXiv:2003.14113},
year = {2020}
}