Magnetic structure

About: Magnetic structure is a research topic. Over the lifetime, 10787 publications have been published within this topic receiving 207143 citations.

Magnetic structure of isospin-asymmetric QCD matter in neutron stars

Abstract: We study QCD under the influence of background magnetic fields and isospin chemical potentials using lattice simulations. This setup exhibits a sign problem which is circumvented using a Taylor expansion in the magnetic field. The ground state of the system in the pion condensation phase is found to exhibit a pronounced diamagnetic response. We elaborate on how this diamagnetism may contribute to the pressure balance in the inner core of strongly magnetized neutron stars. In addition we show that the onset of pion condensation shifts to larger chemical potentials due to the enhancement of the charged pion mass for growing magnetic fields. Finally, we summarize the magnetic nature of QCD matter on the temperature-isospin chemical potential phase diagram.

Density functional simulation of small Fe nanoparticles

Abstract: We calculate from first principles the electronic structure, relaxation and magnetic moments of small Fe particles, by applying the numerical local orbitals method in combination with norm-conserving pseudopotentials. The accuracy of the method in describing elastic properties and magnetic phase diagrams is tested by comparing benchmark results for different phases of crystalline iron to those obtained by an all-electron method. Our calculations for the bipyramidal Fe5 cluster confirm previous plane-wave results that predicted a non-collinear magnetic structure. For larger bcc-related (Fe35, Fe59) and fcc-related (Fe38, Fe43, Fe55, Fe62) particles, a larger inward relaxation of outer shells has been found in all cases, accompanied by an increase of local magnetic moments on the surface to beyond 3 \(\mu_{\scriptstyle{B}}\).

Neutron diffraction study of unusual phase separation in the antiperovskite nitride Mn3ZnN.

Abstract: The antiperovskite Mn(3)ZnN is studied by neutron diffraction at temperatures between 50 and 295 K. Mn(3)ZnN crystallizes to form a cubic structure at room temperature (C1 phase). Upon cooling, another cubic structure (C2 phase) appears at around 177 K. Interestingly, the C2 phase disappears below 140 K. The maximum mass concentration of the C2 phase is approximately 85% (at 160 K). The coexistence of C1 and C2 phase in the temperature interval of 140-177 K implies that phase separation occurs. Although the C1 and C2 phases share their composition and lattice symmetry, the C2 phase has a slightly larger lattice parameter (Δa ≈ 0.53%) and a different magnetic structure. The C2 phase is further investigated by neutron diffraction under high-pressure conditions (up to 270 MPa). The results show that the unusual appearance and disappearance of the C2 phase is accompanied by magnetic ordering. Mn(3)ZnN is thus a valuable subject for study of the magneto-lattice effect and phase separation behavior because this is rarely observed in nonoxide materials.

Magnetic and crystal structure of the novel compound Nd3Fe29−xTix

Abstract: The structure of the compound previously reported as Nd2Fe19−xTix has been solved by powder neutron diffraction, which reveals a monoclinic cell and a stoichiometry of Nd3Fe29−xTix (x=1.24) and two formula units per unit cell. This low symmetry, and the large number of crystallographically unique sites (17), lead to a wide range of Fe—Fe bond lengths (from 2.36 to 3.01 A) in a nearly continuous band. The phase forms through the replacement of two‐fifths of the rare earths in the RFe5 phase by Fe‐Fe dumbbells. The magnetic moments at room temperature lie along the monoclinic a axis with an average iron moment of 1.05 μB, while the magnetic moments at 12.5 K lie in the a‐b plane with an average iron moment of about 1.36 μB.