Observation of Band-Splitting by Paramagnetic Spin-Fluctuations in EuZn2Sb2*

The simultaneous presence of time-reversal symmetry and spatial inversion symmetry imposes a two-fold degeneracy of the bands structure of a solid. Typically, the lifting of this degeneracy in centrosymmetric materials is indicative of long-range magnetization. However, correlated alignment of spins, even in a paramagnetic sample, is also capable of lifting the spin-degeneracy of the electronic states. We report the observation of parallelly dispersing split bands in Eu-ternary pnictide EuZn2Sb2 through the use of high-resolution ARPES. Our DFT calculations account for the observed splitting by including the effects of long-range ferromagnetic correlation of the spins. These results indicate the possibility of observing further time-reversal violating physics in non-magnetic materials.