scholarly journals Bad neighbour, good neighbour: how magnetic dipole interactions between soft and hard ferrimagnetic nanoparticles affect macroscopic magnetic properties in ferrofluids

Nanoscale ◽  
2020 ◽  
Vol 12 (20) ◽  
pp. 11222-11231 ◽  
Author(s):  
Niéli Daffé ◽  
Jovana Zečević ◽  
Kalliopi N. Trohidou ◽  
Marcin Sikora ◽  
Mauro Rovezzi ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Dipole ◽  
Dipole Interactions ◽  
Ferrimagnetic Nanoparticles

Hard ferrimagnetic CoFe2O4 nanoparticles become softer in the presence of neighbouring soft ferrimagnetic MnFe2O4 nanoparticles.

scholarly journals Magnetic-dipole corrections to RK and RK* in the Standard Model and dark photon scenarios

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Emidio Gabrielli ◽  
Marco Palmiotto
Keyword(s):  
Magnetic Dipole ◽  
New Physics ◽  
Mass Region ◽  
Long Distance ◽  
Lepton Flavor ◽  
Dark Photon ◽  
Dipole Interactions ◽  
Decay Widths ◽  
Charged Leptons ◽  
Inclusive Decay

Abstract In this work we evaluate the long-distance QED contributions, induced by the magnetic-dipole corrections to the final charged leptons, on the B meson decay widths B → (K, K*)ℓ+ℓ− and ratios RK,K* = Γ(B → (K, K*)μ+μ−)/Γ(B → (K, K*)e+e−), as well as on $$ {R}_{K,K\ast}^{\tau } $$ R K , K ∗ τ (with μ replaced by the τ lepton). QED long-distance contributions induced by the Coulomb potential corrections (Fermi-Sommerfeld factors) were also included. Corresponding corrections to the inclusive decay widths of B → Xsℓ+ℓ−, with ℓ = e, μ, τ, are also analyzed for completeness. The magnetic-dipole corrections, which are manifestly Lepton Flavor Universality violating and gauge-invariant, are expected to be particularly enhanced in RK* for the dilepton mass region close to the threshold. However, we find that the largest contribution of all these corrections to the RK,K* observables do not exceed a few per mille effect, thus reinforcing the validity of previous estimates about the leading QED corrections to RK,K*. Finally, viable new physics contributions to RK,K* induced by the exchange of a massless dark-photon via magnetic-dipole interactions, which provide the leading contribution to the corresponding B → (K, K*)ℓ+ℓ− amplitudes in this scenario, are analyzed in light of the present RK,K* anomalies.

Magnetic dipole interactions in dysprosium ethyl sulphate - I. Susceptibility and specific heat between 20 and 1°K

1959 ◽  
Vol 252 (1269) ◽  
pp. 246-259 ◽  
Keyword(s):  
Specific Heat ◽  
Magnetic Dipole ◽  
Ground State ◽  
Optical Rotation ◽  
Dipole Interaction ◽  
Crystal Axis ◽  
Dipole Interactions ◽  
Degenerate Ground State ◽  
Magnetic Ions ◽  
Good Agreement

Measurements have been made of the magnetic susceptibility and the magnetic contributions to the specific heat of dysprosium ethyl sulphate, at temperatures between 20 and 1°K. It is shown that below about 3°K these properties, and also the earlier optical rotation measure­ments of Becquerel et al ., can be accounted for satisfactorily in terms of a doubly degenerate ground state of the magnetic ions, with spectroscopic splitting factors parallel and perpen­dicular to the crystal axis g 1 = 10.8 and g ┴ = 0, together with an unusually strong coupling between the ions arising from magnetic dipole-dipole interaction. The effect of other inter­actions is shown to be small. Because of this, and the extreme anisotropy of the g -tensor, the properties of this substance at very low temperatures (~ 0.1°K) should closely resemble those of a classical Ising model with known, dipolar forces between the ions. At temperatures above 3°K other states of the ions become populated and it is shown that the first of these lies at an energy of (23 ± 3) k , in good agreement with other experiments.

scholarly journals superhyperfine structure due to magnetic dipole–dipole interactions with in

2010 ◽  
Vol 130 (9) ◽  
pp. 1594-1597 ◽  
Author(s):  
R.L. Ahlefeldt ◽  
W.D. Hutchison ◽  
M.J. Sellars
Keyword(s):  
Magnetic Dipole ◽  
Superhyperfine Structure ◽  
Dipole Interactions
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