# CeAu$_{2}$Bi: a new nonsymmorphic antiferromagnetic compound

## TL;DR

This paper introduces CeAu$_{2}$Bi, a new nonsymmorphic antiferromagnetic heavy-fermion compound with unique electronic and magnetic properties, including pressure-dependent ordering temperature and symmetry-protected band crossings.

## Contribution

The study characterizes the structural, magnetic, and electronic properties of CeAu$_{2}$Bi, revealing its nonsymmorphic structure, localized f-electrons, and topologically protected band crossings.

## Key findings

- Antiferromagnetic order below 3.1 K with a hard c-axis
- Pressure increases the Néel temperature at 0.07 K/kbar
- Presence of symmetry-protected band crossings at $k_z=\pi$

## Abstract

Here we report the structural and electronic properties of CeAu$_{2}$Bi, a new heavy-fermion compound crystallizing in a nonsymmorphic hexagonal structure ($P63/mmc$). The Ce$^{3+}$ ions form a triangular lattice which orders antiferromagnetically below $T_{N} = 3.1$~K with a magnetic hard axis along the c-axis. Under applied pressure, $T_{N}$ increases linearly at a rate of $0.07$~K/kbar, indicating that the Ce $f$-electrons are fairly localized. In fact, heat capacity measurements provide an estimate of 150(10) mJ/mol.K$^{2}$ for the Sommerfeld coefficient. The crystal-field scheme obtained from our thermodynamic data points to a ground state with dominantly $|j_{z}=\pm1/2\rangle$ character, which commonly occurs in systems with a hard c-axis. Finally, electronic band structure calculations and symmetry analysis in $k$-space reveal that CeAu$_{2}$Bi hosts symmetry-protected crossings at $k_{z} = \pi$ in the paramagnetic state