Spin-flop ordering

OX or OY axis [11], The magnetic ordered phase T45 in the Cui xZnxGe02 realizes at H < Hsj, and at II > IIsj the spin-flop phase I47 takes place, because OX axis is the second easy axis [9], When the magnetic field becomes H Hex Jc the second order phase transition... 

It should be taken into account that even while the spin-flop transition possesses the character of a 1-st order phase transition at a precise alignment of the magnetic field along the z-axis, the character of the 1-st order transition is lost when h tilts away from the z-axis by an angle larger than a certain critical value ipc. The critical angle value is deter-... 

The spin-flop transition in M11F2 is of first order at ip < -i/y 30 only. Extremely fine orientation of the magnetic field relative to the crystal axis should be achieved (as the permitted error should not exceed several angular minutes). For this reason the solenoid is mounted on a separate plate, and its slope is varied by 4 micrometer screws. 

The domain structure, which appears in MnF2 at the spin-flop transition illustrates a general thermodynamic law of intermediate state formation in the process of first-order phase transitions, induced by a magnetic field, and under the condition that the surface energy of the interface boundary (a > 0) is positive. 

When increasing the value of H, the moments gradually rotate towards the applied field direction and when H = Hc, they are parallel to the field. In the molecular field model, the spin-flop is a first-order transition and the spin flop 5 paramagnetic transition a second-order process. Between HSF and Hc magnetization increases linearly with H M/Ms = H (2HE - Ha) where Ms is the saturation magnetization of a sublattice (Ms = A NgMBS). At T = 0 K, the critical field can be written as HSF = [2HE HA/(1 - a)]1/2... 

Classic order-disorder, spin flops, electronic localization, and percolation... 

Classic order-disorder, spin flops, electronic localization, and percolation Frustration and magneto-strain effects Magneto-volume effects Exotic effects and transitions OVERVIEW OF RECENT DEVELOPMENTS... 

The worm and directed loop algorithms are applied when magnetic fields are present. Typical examples include the calculation of magnetization curves of quantum magnets [74], the determination of the first order nature of the spin flop transition in two dimensions [75] and the calculation of phase diagrams of dimerized quantum magnets in a magnetic field [76]. 

Fig. 49. Schematic phase diagrams predicted for the antiferromagnetic order at the surfaces of isotropic Heisenberg magnets (n = 3, upper part) and of XY magnets (n = 2), lower part. Phases occurring are bulk paramagnetic (BP), bulk ferromagnetic (BP), surface paramagnetic (A P), surface ferromagnetic (A P), surface antifcrromagnctic (SAF) and surface spin flop (iSSF). From Binder and Landau (1985).

The use of analytical models for spin dephasing in the solid state [39, 40] is not appropriate for the present case because they do not account for the specific distribution of nuclear spins around the electron spin. In order to consider the real matrix structure close to the chromophore we simulated the HE decay curves numerically by using the known crystal structure [9] and the nuclear flip-flop rate IE as a parameter. The echo decay is calculated as... 

This feature is sketched in fig. 19. Thus, a vector spin system in a field H within the SK model exhibits a phase with spin-glass order transverse to the field, reminiscent of a spin-flop phase of a pure antiferromagnet. Just below the GT line, only weak irreversibilty occurs in the longitudinal component but there is a crossover to strong irreversibility in at a region which goes as like the AT line (indicated by the dashed line in fig. 19). 

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