Related Experiment Video
Updated: May 31, 2026
11:54
Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures
Published on: February 8, 2018
Frustrated spin correlations in diluted spin ice Ho(2-x)La(x)Ti(2)O(7)
G Ehlers1, E Mamontov, M Zamponi
1Spallation Neutron Source, Oak Ridge National Laboratory, Building 8600, Oak Ridge, TN 37831-6475, USA.
Summary
Diluting Ho(2)Ti(2)O(7) spin ice with La preserves the pyrochlore structure but introduces local disorder. Dynamic spin correlations persist, with an additional faster relaxation process observed in diluted samples.
Area of Science:
- Condensed matter physics
- Materials science
- Magnetism
Background:
- Spin ice materials exhibit unique magnetic properties due to frustrated spin interactions.
- Ho(2)Ti(2)O(7) is a model system for studying emergent phenomena in frustrated magnets.
- Partial substitution with non-magnetic ions allows tuning of magnetic properties.
Purpose of the Study:
- To investigate the structural and magnetic properties of Ho(2-x)La(x)Ti(2)O(7) spin ice.
- To understand the impact of non-magnetic La dilution on spin correlations and dynamics.
- To characterize the evolution of local disorder with increasing La concentration.
Main Methods:
- X-ray and neutron diffraction for structural characterization.
- Extended X-ray Absorption Fine Structure (EXAFS) at Ho L(III) and Ti K edges to probe local disorder.
- Quasi-elastic neutron scattering and AC susceptibility measurements for spin correlation and dynamics analysis.
Main Results:
- The pyrochlore structure remains intact up to La concentration x = 0.3.
- Increased local disorder is observed with increasing La concentration, particularly from Ti K-edge EXAFS.
- Short-ranged, dynamic spin-spin correlations are present above macroscopic freezing temperatures for x ≤ 0.4.
- A secondary, faster relaxation process emerges in the dynamics of diluted samples.
Conclusions:
- Partial substitution of Ho with La in Ho(2)Ti(2)O(7) spin ice leads to controlled structural and magnetic property modifications.
- The observed local disorder and altered spin dynamics provide insights into the behavior of frustrated magnetic systems.
- The findings contribute to the understanding of magnetic correlations and relaxation mechanisms in diluted spin ice.
Related Concept Videos
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:08Spin–Spin Coupling Constant: Overview
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 have a...
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 have a...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:17Spin–Spin Coupling: One-Bond Coupling
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,...
02:54Trends in Lattice Energy: Ion Size and Charge
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
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...