LAUSR

A wide range of metals exhibit anomalous electrical and thermodynamic properties when tuned to a quantum critical point (QCP), although the origins of such strange metals have posed a long-standing mystery. The frequent association of strange metals with unconventional superconductivity and antiferromagnetic QCPs 1 – 4 has led to the belief that they are highly entangled quantum states 5 . By contrast, ferromagnets are regarded as an unlikely setting for strange metals, because they are weakly entangled and their QCPs are often interrupted by competing phases or first-order phase transitions 6 – 8 . Here we provide evidence that the pure ferromagnetic Kondo lattice 9 , 10 CeRh 6 Ge 4 becomes a strange metal at a pressure-induced QCP. Measurements of the specific heat and resistivity under pressure demonstrate that the ferromagnetic transition is continuously suppressed to zero temperature, revealing a strange-metal behaviour around the QCP. We argue that strong magnetic anisotropy has a key role in this process, injecting entanglement in the form of triplet resonating valence bonds into the ordered ferromagnet. We show that a singular transformation in the patterns of the entanglement between local moments and conduction electrons, from triplet resonating valence bonds to Kondo-entangled singlet pairs at the QCP, causes a jump in the Fermi surface volume—a key driver of strange-metallic behaviour. Our results open up a direction for research into ferromagnetic quantum criticality and establish an alternative setting for the strange-metal phenomenon. Most importantly, strange-metal behaviour at a ferromagnetic QCP suggests that quantum entanglement—not the destruction of antiferromagnetism—is the common driver of the varied behaviours of strange metals. The ferromagnet CeRh 6 Ge 4 is found to exhibit strange-metal behaviour at a quantum critical point, suggesting that changes in the pattern of quantum entanglement, not antiferromagnetism, underlie the development of strange metals.