Studies on Successive Electronic State Changes in Systems with NiO₂ Planes–139La-NMR/NQR–

摘要

139 La-NMR/NQR measurements of La₃Ni₂O₇-δ (δ∼0.0 and δ∼0.08), and La₄Ni₃O₁₀ have been performed. 139 La-NMR and transport and magnetic studies have also been carried out for Tl(La₂Sr₂ )Ni₂O₉. Anomalous temperature ( T ) dependence of the longitudinal relaxation rates 1/T₁ has been found at temperatures T A ∼(140–150 K) for all the systems. In Tl(La₂Sr₂ )Ni₂O₉, there exists a transition to a magnetically ordered state at T ∼20 K. The large broadening of the NMR spectra observed for Tl(La₂Sr₂ )Ni₂O₉ below 20 K indicates that the system is in the charge ordered state in the temperature region between 20 K and T A with localized magnetic moments at Ni sites. The NQR intensity of La₄Ni₃O₁₀ begins to decrease rapidly with decreasing T at T A ∼140 K and almost disappears at T ∼120 K (wipeout). B_y arguing results of the present experimental studies, we propose that in all the systems with NiO 2 planes studied here exhibit similar type transitions to the charge ordered states at temperatures T A, all of which are in the narrow T region around 140 K. It has also been found that all the systems exhibit resistivity anomalies in the T region of (450–550) K, which suggests that they have a tendency of similar type changes or transitions of their electronic states at the temperatures, too.

材料

• La₃Ni₂O₇-δ
• La₄Ni₃O₁₀
• Tl(La₂Sr₂)Ni₂O₉

方法

• 139La NMR/NQR

关键词

• charge ordered state
• wipeout
• nio2 planes
• resistivity anomalies

亮点

• First observation of wipeout in La₄Ni₃O₁₀ associated with charge order.

结论

• All systems exhibit similar type transitions to charge ordered states at temperatures T_A around 140 K.
• NQR intensity wipeout in La₄Ni₃O₁₀ indicates charge order with localized moments.
• Resistivity anomalies in the 450-550 K range suggest additional electronic state changes.

主要论断

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研究流程

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