Charge-stripe order, antiferromagnetism, and spin dynamics in the cuprate-analog nickelate La${}_4$Ni${}_3$O${}_8$

Abstract

We report a muon spin rotation ($\hat{I}¼$SR) study of the cuprate-analog nickelate La${}_4$Ni${}_3$O${}_8$, which undergoes a transition at 105 K to a low-temperature phase with charge-stripe and antiferromagnetic (AFM) order on square planar NiO${}_2$ layers. Zero-field $\hat{I}¼$SR shows that this transition is abrupt and that the AFM configuration is commensurate. Comparison of observed muon precession frequencies with Ni dipolar field calculations yields Ni moments $\lesssim 0.5\hat{I}{¼}_B$. Dynamic muon spin relaxation above 105 K suggests critical slowing of Ni spin fluctuations, but is inconsistent with corresponding ${}^{139}$La NMR results. Critical slowing and an abrupt transition are also observed in the planar cuprate AFM La${}_2$CuO${}_{4+\hat{I}´}$, where they are evidence for weakly interplanar-coupled two-dimensional AFM spin fluctuations, but our $\hat{I}¼$SR data do not agree quantitatively with theoretical predictions for this scenario.

17 pages, 25 figures, 49 references; under review by PRB