We have performed high-pressure magnetotransport and x-ray diffraction measurements on ferromagnetic $\mathrm{LaC}{\mathrm{o}}_5$, confirming the theoretically predicted electronic topological transition driving the magnetoelastic collapse seen in the related compound $\mathrm{YC}{\mathrm{o}}_5$. Our x-ray diffraction results show an anisotropic lattice collapse of the $c$ axis near 10 GPa that is also commensurate with a change in the majority charge carriers evident from high-pressure Hall effect measurements. The coupling of the electronic, magnetic, and lattice degrees of freedom is further substantiated by the evolution of the anomalous Hall effect, which couples to the magnetization of the ordered state of $\mathrm{LaC}{\mathrm{o}}_5$.

• Received 10 August 2015
• Revised 4 November 2015

DOI:https://doi.org/10.1103/PhysRevB.92.174421