Knowledge

La₅Ni₄O₁₃

1 linked paper

La₅Ni₄O₁₃₊δ

1 linked paper

La₆Ni₅O₁₂

3 linked papers

La₆Ni₅O₁₆

1 linked paper

La₇Ni₅O₁₇

1 linked paper

LaNiO₂

6 linked papers

LaNiO₃

3 linked papers

LaPdO₂

1 linked paper

large tiny spin stripe

1 linked paper

Large-Tiny Spin-Stripe SDW Order in La₃Ni₂O₇ via ¹³⁹La-NQR Spectroscopy: Reconsideration Based on the Am2m Structure

This study employs $^{139}$La nuclear quadrupole resonance (NQR) spectroscopy to re-examine the crystal structure and spin density wave (SDW) state of ambient-pressure bilayer nickelate La$_3$Ni$_2$O$_7$. The experimental observation of two distinct La(2) sites is naturally explained within the low-symmetry $Am2m$ structural framework, whereas previous defect models based on the $Amam$ structure fail to provide a self-consistent description. Within the $Am2m$ structure, the SDW spin configuration is re-identified as a “large-small” spin stripe structure, arising from the distinct large and small magnetic moments associated with two inequivalent Ni sites. Based on DFT+U calculations and NQR parameter analysis, the study confirms the itinerant nature of this SDW order, indicating that it is driven by Fermi surface nesting rather than local magnetic moment mechanisms, thereby providing a foundation for understanding the origin of high-$T_c$ superconductivity in this material under high pressure.