Related Experiment Video
Updated: Feb 6, 2026
08:03
Study of Protein Dynamics via Neutron Spin Echo Spectroscopy
Published on: April 13, 2022
2.6K
μSR study of spin freezing and persistent spin dynamics in NaCaNi2F7
Y Cai1, M N Wilson1, A M Hallas1
1Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada.
Summary
Researchers studied the magnetic properties of NaCaNi2F7 using muon spin rotation. They observed spin freezing into a disordered state below 4 K, with ongoing spin dynamics at low temperatures.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- The pyrochlore compound NaCaNi2F7 features a single magnetic site with spin-1 Ni2+ ions.
- Geometric frustration in magnetic systems often leads to complex spin dynamics and disordered ground states.
Purpose of the Study:
- To investigate the magnetic properties and spin dynamics of the newly synthesized pyrochlore NaCaNi2F7.
- To determine the ground state magnetic ordering and low-temperature behavior of the Ni2+ spins.
Main Methods:
- Muon spin rotation (μSR) spectroscopy was employed under zero field and longitudinal field conditions.
- Density functional theory (DFT) calculations were performed to identify the most probable muon site.
Main Results:
- Muon spin polarization measurements revealed characteristic F-μ-F interactions at high temperatures due to rapid Ni spin fluctuations.
- The Ni2+ spins exhibit spin freezing into a disordered ground state below 4 K, characterized by an internal field of 140 G.
- Evidence of persistent Ni spin dynamics was observed down to 75 mK, consistent with geometrically frustrated magnetic systems.
Conclusions:
- NaCaNi2F7 displays a disordered magnetic ground state, a common characteristic of frustrated pyrochlores.
- The persistent spin dynamics at low temperatures highlight the influence of geometric frustration on the magnetic behavior of this compound.
Related Concept Videos
01:08NMR Spectroscopy: Spin–Spin Coupling
3.2K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
3.2K
01:17Spin–Spin Coupling: One-Bond Coupling
1.5K
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
1.5K
01:08Spin–Spin Coupling Constant: Overview
1.5K
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
1.5K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.7K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
1.7K
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.5K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
1.5K
01:08Atomic Nuclei: Nuclear Spin
5.2K
All atomic particles possess an intrinsic angular momentum, or 'spin'. Electrons, protons, and neutrons each have a spin value of ½, although protons and neutrons in nuclei may have higher half-integer spins owing to energetic factors.
Atomic nuclei have a net nuclear spin, , which can have an integer or half-integer value. In atomic nuclei, the spins of protons are paired against each other but not with neutrons, and vice versa. Consequently, an even number of protons does not contribute to...
Atomic nuclei have a net nuclear spin, , which can have an integer or half-integer value. In atomic nuclei, the spins of protons are paired against each other but not with neutrons, and vice versa. Consequently, an even number of protons does not contribute to...
5.2K