Susceptibility and NQR investigations on NaCuO2

Riesemeier, H.; Gärtner, S.; Lüders, Klaus; Schmalz, Michael J.; Schöllhorn, R.

doi:10.1016/0022-3697(94)90060-4

Cited by 10 publications

(5 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such squareplanner coordinated trivalent copper cations can also been found in MCuO 2 (M ¼ Li, Na, K), which behave as diamagnets. [18][19][20] It should be noted that the unusual Cu 3+ might be better described as a d 9 L configuration, due to its low-lying d level with a covalent electronic state and a ligand hole L. 21 This d 9 L configuration is known to form singlet between the cation and the ligand (Zang-Rice singlet, as seen in CaCu 3 Co 4 O 12 and YCu 3 Co 4 O 12 ), 22 in which the cation shows nonmagnetic behavior as well.…”

Section: Magnetic Structurementioning

confidence: 99%

Charge transfer and antiferromagnetic order in the A-site-ordered perovskite LaCu3Fe4O12

et al. 2010

View full text Add to dashboard Cite

Section: Magnetic Structurementioning

confidence: 99%

Charge transfer and antiferromagnetic order in the A-site-ordered perovskite LaCu3Fe4O12

et al. 2010

View full text Add to dashboard Cite

“…All precursors of the reaction described by Eq. 2 are insulators, with sizeable band gaps; the calculated band gap approaches 2.2 eV for antiferromagnetic CaCuO 2 , exceeds 2.4 eV for low-spin [ 33 ] NaCuO 2 with its totally empty d(x 2 –y 2 ) / p x ,p y σ* conduction band, and is even larger than 4.0 eV for LaCuO 2 , the d 10 system. On the other hand, metallic spin-unpolarized solutions of the doped systems show appreciable DOS(E F ) values [ 34 ], which stems mostly from partial occupation of the nearly half-filled d(x 2 –y 2 ) / p x ,p y σ* band, doped at ±12.5%.…”

Section: Resultsmentioning

confidence: 98%

High-temperature superconductivity as viewed from the maximum hardness principle

Grochala

Derzsi

2018

J Mol Model

View full text Add to dashboard Cite

The Maximum Hardness Principle – and its reformulation by Chattaraj as the Minimum Polarizability Principle – is an immensely useful concept which works in support of a chemical intuition. As we show here, it may also be used to rationalize the scarcity of high-temperature superconductors, which stems – inter alia – from rarity of high-density of state metals in Nature. It is suggested that the high-temperature oxocuprate superconductors as well as their iron analogues – are energetically metastable at T ➔ 0 K and p ➔ 0 atm conditions, and their tendency for disproportionation is hindered only by the substantial rigidity of the crystal lattice, while the phase separation and/or superstructure formation is frequently observed in these systems. This hypothesis is corroborated by hybrid density functional theory theoretical calculations for Na- (thus: hole) or La- (thus: electron) doped CaCu(II)O2 precursor. Non-equilibrium synthetic methods are suggested to be necessary for fabrication of high-temperature superconductors of any sort. Graphical abstractDoped oxocuprate superconductors are shown to be unstable with respect to phase separation (disproportionation) in accordance with the Maximum Hardness Principle; their metastability is mostly due to rigidity of [CuO2] sheets and preparation using high-temperature conditions

show abstract

“…In spite of the singlets, the nuclear spin-lattice relaxation time is relatively short. For Li-substituted La 2 CuO 4 [45] and NaCuO 2 [46], nonmganetic Cu 3+ NQR signals are observed to be in low spin electronic states. The observed magnetism of Cu 2+δ of 3d 9 L ¯is different from Cu 3+ so far.…”

Section: Magnetic Phase Diagram a Two Dimensional Renormalized Classi...mentioning

confidence: 94%

Recent advances of NMR and NQR studies of YBa2Cu3O7-d and YBa2Cu4O8

Itoh

2007

Preprint

View full text Add to dashboard Cite

Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) techniques have supplied us with unique information on local incoherent phenomenon as well as low frequency magnetic response of electronic systems. Some of recent advances in the studies of high-Tc cuprate superconductors are based on site-selective measurements of the local electronic state and the local electron spin dynamics. High-Tc superconductors YBa2Cu3O 7−δ (the optimal Tc = 93 K) and YBa2Cu4O8 (Tc = 82 K) with double-layer CuO2 planes have been studied by NMR and NQR techniques. From the intensive studies at the early stage, two-dimensional antiferromagnetic spin fluctuations and pseudo spin-gap in the magnetic excitation spectrum turned out to be key ingredients to characterize the novel electronic states, associated with the occurrence of superconductivity. Wipeout effect is a new key to characterize superconductor-insulator boundary in the lightly doped regime and impurity substitution effects. What happens near in-plane impurities and inside vortex cores in such novel electronic states? Nonmagnetic impurity Zn decreases Tc of the d-wave superconductivity because of the breakdown of Anderson theorem. From the careful NMR and NQR studies, it was concluded that the pseudo spin-gap in the normal state is robust for the substitution of nonmagnetic impurity Zn and magnetic impurity Ni. In the vicinity of a superconductor-insulator boundary induced by impurity, however, the pseudo spin-gap is suppressed. Collapse of low energy pseudo spin-gap due to the heavily substituted impurity Zn was also evidenced by neutron scattering measurements. For the impurity-substituted samples and in the vortex state of pure samples, the characteristic NMR and NQR spectra were observed. The local enhancement of magnetic correlation near the impurity Zn and inside the vortex core was observed from the frequency distribution of nuclear spin-lattice relation time T1. Scanning tunneling spectroscopy detects local density of states of electrons near Zn in the superconducting state. NMR and NQR experiments detect the local magnetism near Zn and inside the vortex cores.

show abstract

Susceptibility and NQR investigations on NaCuO2

Cited by 10 publications

References 7 publications

Charge transfer and antiferromagnetic order in the A-site-ordered perovskite LaCu3Fe4O12

Charge transfer and antiferromagnetic order in the A-site-ordered perovskite LaCu3Fe4O12

High-temperature superconductivity as viewed from the maximum hardness principle

Recent advances of NMR and NQR studies of YBa2Cu3O7-d and YBa2Cu4O8

Contact Info

Product

Resources

About