Search results for "Spin density wave"
showing 3 items of 3 documents
Nature of the phase transition in spin crossover compounds
1990
Abstract Starting from the phenomenological free energy describing the spin equilibrium of continuous or gradual high spin (HS) ⇌ low spin (LS) transitions a reduced equation of state has been derived which is of the type known in mean field theories. The continuous HS ⇌ LS transitions of [Fe(2-pic-ND 2 ) 3 ]Cl 2 ·EtOD (2-pic = 2-picolylamine) at ambient pressure and p = 1200 bar and of [Fe(2-pic) 3 ]Cl 2 -MeOH can be classified as isobars above the critical point of the system. Around and below the critical point a complex behaviour is expected for thermodynamic reasons combined with the consequences of an elastic interaction mechanism between the HS and LS complex molecules in the crystal…
Dzyaloshinskii-Moriya Interaction and Hall Effects in the Skyrmion Phase ofMn1−xFexGe
2015
We carry out density functional theory calculations which demonstrate that the electron dynamics in the Skyrmion phase of Fe-rich Mn_{1-x}Fe_{x}Ge alloys is governed by Berry phase physics. We observe that the magnitude of the Dzyaloshinskii-Moriya interaction directly related to the mixed space-momentum Berry phases, changes sign and magnitude with concentration x in direct correlation with the data of Shibata et al. [Nat. Nanotechnol. 8, 723 (2013)]. The computed anomalous and topological Hall effects in FeGe are also in good agreement with available experiments. We further develop a simple tight-binding model able to explain these findings. Finally, we show that the adiabatic Berry phase…
Strong reduction of the Korringa relaxation in the spin-density wave regime ofEuFe2As2observed by electron spin resonance
2010
Electron spin resonance measurements in ${\text{EuFe}}_{2}{\text{As}}_{2}$ single crystals revealed an absorption spectrum of a single resonance with Dysonian line shape. Above the spin-density wave (SDW) transition at ${T}_{\text{SDW}}=190\text{ }\text{K}$ the spectra are isotropic and the Eu spins relax via the conduction electrons resulting in a Korringa-type increase in the linewidth. Below ${T}_{\text{SDW}}$, a distinct anisotropy develops and the relaxation behavior of the Eu spins changes drastically into one with characteristic properties of a magnetic insulating system, where dipolar and crystal-field interactions dominate. This indicates a spatial confinement of the conduction ele…