Pressure-Invariant Isotope Effect as Evidence for Electronically Driven Intertwined Order in Pr$_4$Ni$_3$O$_{10}$

TL;DR

This study investigates how pressure affects the oxygen isotope effect on the spin-density wave transition in Pr4Ni3O10, revealing a pressure-invariant isotope effect that indicates an electronically driven intertwined order.

Contribution

It provides evidence that the SDW transition in Pr4Ni3O10 is predominantly electronically driven, based on pressure-invariant isotope effects observed through muon-spin rotation measurements.

Findings

Isotope shift remains unchanged under pressure.

SDW transition decreases linearly with pressure for both isotopes.

Supports electronically driven intertwined order in trilayer nickelates.

Abstract

We report muon-spin rotation measurements of the pressure dependence of the oxygen-isotope ($^{16}$O/$^{18}$O) effect on the spin-density wave (SDW) transition in the trilayer Ruddlesden-Popper nickelate Pr$_4$Ni$_3$O$_{10}$. At ambient pressure, the SDW transition shows a finite isotope shift, with $^{16}T_{\rm SDW}=158.04(5)$ K and $^{18}T_{\rm SDW}=159.81(6)$ K. Under hydrostatic pressure, $T_{\rm SDW}$ decreases linearly at nearly identical rates for the two isotope compositions, ${\rm d}\,^{16}T_{\rm SDW}/{\rm d}p=-4.93(5)$ K/GPa and ${\rm d}\,^{18}T_{\rm SDW}/{\rm d}p=-4.90(7)$ K/GPa, such that the isotope shift remains essentially unchanged under compression. The absence of pressure enhancement of the isotope effect points to a predominantly electronic origin of the SDW transition and is consistent with recent inelastic x-ray scattering results, suggesting a new regime of intertwined order in trilayer RP nickelates, which is stabilized by strong spin interactions.