Search results for "Magnetic dipole–dipole interaction"
showing 10 items of 13 documents
Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance
2015
Zero- to ultra-low-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero- to ultra-low-field NMR measurements of residual dipolar couplings in acetonitrile…
Lateral indirect exchange coupling in a two-dimensional nanostripe array
2002
We observe a lateral indirect exchange coupling in a multistripe system of parallel Fe nanostripes grown by self-organized growth on a vicinal single-crystal W(110) surface. The width and the distance between the stripes of monolayer height were modified via the total amount of deposited Fe. The easy axis of the magnetization lies perpendicular to the stripe edges and in the surface plane, thus resulting in a ferromagnetic dipolar coupling. In addition to the dipolar coupling we observe an antiferromagnetic indirect exchange coupling for the nanostripe system covered by Au. The coupling causes a superferromagnetic phase transition in the nanostripe array.
Dipolar coupling of nanoparticle-molecule assemblies: An efficient approach for studying strong coupling
2021
Strong light-matter interactions facilitate not only emerging applications in quantum and non-linear optics but also modifications of materials properties. In particular the latter possibility has spurred the development of advanced theoretical techniques that can accurately capture both quantum optical and quantum chemical degrees of freedom. These methods are, however, computationally very demanding, which limits their application range. Here, we demonstrate that the optical spectra of nanoparticle-molecule assemblies, including strong coupling effects, can be predicted with good accuracy using a subsystem approach, in which the response functions of the different units are coupled only a…
Antiferromagnetic Insulatronics: spintronics without magnetic fields
2021
While known for a long time, antiferromagnetically ordered systems have previously been considered, as expressed by Louis Neel in his Nobel Prize Lecture, to be “interesting but useless”. However, since antiferromagnets potentially promises faster operation, enhanced stability with respect to interfering magnetic fields and higher integration due to the absence of dipolar coupling, they could potentially become a game changer for new spintronic devices. The zero net moment makes manipulation using conventional magnetic fields challenging. However recently, these materials have received renewed attention due to possible manipulation based on new approaches such as photons or spin-orbit torqu…
Magnetic Anisotropies and Coupling Mechanisms inFe/Mo(110)Nanostripes
2005
Using low-temperature (5 K) spin-polarized scanning tunneling microscopy, we have studied the morphology and magnetic properties of monolayer (ML) and double layer (DL) thick Fe nanowires grown by step flow on a Mo(110) single crystal. Magnetic contrast has been obtained using tungsten tips covered by Au/Co thin films. We find that the DL Fe nanowires, similarly to ML Fe nanowires, are perpendicularly magnetized. Because of the dipolar coupling, separated DL Fe nanowires are antiferromagnetically coupled. DL wires that are touching at step edges are ferromagnetically ordered due to direct exchange coupling. We measured the widths of the magnetic domain walls in the ML and DL Fe nanowires. T…
Polarized neutron reflectivity from monolayers of self-assembled magnetic nanoparticles
2015
We prepared monolayers of iron oxide nanoparticles via self-assembly on a bare silicon wafer and on a vanadium film sputter deposited onto a plane sapphire substrate. The magnetic configuration of nanoparticles in such a dense assembly was investigated by polarized neutron reflectivity. A theoretical model fit shows that the magnetic moments of nanoparticles form quasi domain-like configurations at remanence. This is attributed to the dipolar coupling amongst the nanoparticles.
Dipolar superferromagnetism in monolayer nanostripes of Fe(110) on vicinal W(110) surfaces
1998
By epitaxial growth of Fe on a vicinal W~110! substrate, densely spaced and continuous monolayer stripes of Fe~110! were prepared, directed along @001#. They exhibit a sharp phase transition to ferromagnetic order, free from relaxations. The magnetic easy axis is in the plane, but along @110# that means across the stripes. This cross magnetization induces ferromagnetic dipolar coupling between the spin blocks in adjacent stripes, which are preformed by exchange interactions. The resulting superferromagnetic phase transition is therefore driven by dipolar interactions. @S0163-1829~98!52002-4#
Pressure effect on the magnetism of layered copper(II) compounds with interlayer spacing up to 40.7 Å: Nature of the magnetic ordering
2002
The influence of pressure on the structure and magnetic properties of the layered hybrid compounds Cu 2 (OH) 3 (n-C m H 2 m + 1 CO 2 ), zH 2 O is investigated for m = 10 and 12. It is shown that the distance between magnetic copper(II) layers, up to 40.7 A, is not significantly modified and that the temperature of the ferromagnetic ordering decreases linearly with pressure increase. We present a new analysis of the susceptibility data, based on the scaling theory of phase transitions, which clearly shows up a crossover from a high-temperature two-dimensional (2D) behavior to a 3D regime at about 30 K, around 10 K above the long-range ordering temperature. A model of quantum ferromagnetic la…
Theoretical evaluation of lanthanide binding tags as biomolecular handles for the organization of single ion magnets and spin qubits
2015
Lanthanoid complexes are amongst the most promising compounds both in single ion magnetism and as molecular spin qubits, but their organization remains an open problem. We propose to combine Lanthanide Binding Tags (LBTs) with recombinant proteins as a path for an extremely specific and spatially-resolved organisation of lanthanoid ions as spin qubits. We develop a new computational subroutine for the freely available code SIMPRE that allows an inexpensive estimate of quantum decoherence times and qubit–qubit interaction strengths. We use this subroutine to evaluate our proposal theoretically for 63 different systems. We evaluate their behavior as single ion magnets and estimate both decohe…
Dynamics of topological spin structures
2015
Topological spin structures that emerge from the Dzyaloshinskii-Moriya interaction (DMI), such as chiral domain walls and skyrmions have become the focus of intense investigations due to exciting physics and possible applications [1].