English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

I show the infinite-layer rare-earth nickelates are near a structural quantumcritical point by mapping the energetics of their structural instabilitiesusing first priniciples calculations. I first confirm previous results thatshow a phonon instability in the $P4/mmm$ phase leading to the $I4/mcm$structure for $R$NiO$_2$ with $R$ = Sm--Lu. I then study the non-spin-polarizedphonon dispersions of the $I4/mcm$ phase and find that they exhibit rare-earthsize dependent instabilities at the $X$ and $M$ points for materials with $R$ =Eu--Lu. Group-theoretical analysis was used to enumerate all the isotropysubroups due to these instablities, and the distorted structures correspondingto their order parameters were generated using the eigenvectors of the unstablephonons. These structures were then fully relaxed by minimizing both the atomicforces and lattice stresses. I was able to stabilize only five out of thetwelve possible distortions. The $Pbcn$ isotropy subgroup with the $M_5^+(a,a)$order parameter shows noticeable energy gain relative to other distortions forthe compounds with late rare-earth ions. However, the order parameter of thelowest-energy phase switches first to $X_2^- (0,a) + M_5^+ (b,0)$ and then to$X_2^- (0,a)$ as the size of the rare-earth ion is progressively increased.Additionally, several distorted structures lie close in energy for the earlymembers of this series. These features of the structural energetics persisteven when antiferromagnetism is allowed. Such a competition between differentorder parameters that can be tuned by rare-earth ion substitution suggests thatany structural transition that could arise from the phonon instabilitiespresent in these materials can be suppressed to 0 K.

Possible structural quantum criticality tuned by rare-earth ion substitution in infinite-layer nickelates