Magnetic easy axis

Fig. 9. Magnetic field dependence of the magnetization at selected temperatures for a 150-nm thick Ga xMn As film with a Mn composition x = 0.03S. The magnetic field is applied parallel to the sample surface (direction of magnetic easy axis) except for the closed circles at 5 K taken in perpendicular geometry. The solid line for S K shows the magnetization determined from transport measurements. The upper left inset shows a magnified view of the magnetization in the parallel field at 5 K. The lower right inset shows the temperature dependence of the remanent magnetization (Ohno et al. 1996a).

As shown in fig. 9 for the magnetization at 5 K, the magnetic easy axis is in the plane of the film, and shows a weak four-fold symmetry within the plane. The anisotropy energy... 

Fig. 12. Hall resistance Rnal of (a) (Ga,Mn)As/(In,Ga)As and (b) (Ga,Mn)As/GaAs as a function of the magnetic field for various angles between the field and the sample surface normal. (Ga,Mn)As films in (a) and (b) are under tensile and compressive strain, respectively. Clear hysteresis and angle independent heights of the hysteresis in (a) show that magnetic easy axis is perpendicular to the sample surface, whereas the easy axis in (b)...

The anisotropy fluctuations (AK) discussed above typically result from fluctuating orientations of the magnetic easy axis which varies from one grain to another in conventional polycrystalline microstructures, though Eq. (1) is not limited to this mechanism of anisotropy fluctuations. Hence, for conventional polycrystalline materials where 4 > Lcx, the parameter AK introduced into Eq. (1) can be well approximated by the magnetocrystalline anisotropy constant Kh However, as we discuss in the subsequent section, the approximation of AK by K is no longer applicable for small structural correlation lengths. 

Measured along the C-axis (magnetic easy axis). 

Fig., 4.12. Applied field B versus temperature T phase diagrams for a Heisenberg antiferromagnet. The continuous lines represent phase boundaries when the field is applied along the magnetic easy axis and the dashed line represents the phase boundary when the field is perpendicular to this axis.

Fig. 4.13. Spectra of a single crystal of CsjFeCls. HjO at 42K. The applied field is directed along the magnetic easy axis, the a axis, and the gamma-ray beam is directed along the crystal c axis. At B= 1.25 T the antiferromagnetic axis is parallel to the field direction, at B= 1.30 T the spin flop is approximately half completed as indicated by the intensities of the Anti=0 lines and at 1.3ST the spin flop transition is complete with the antiferromagnetic axis now reoriented along the crystal c axis and parallel to the gamma-ray beam. In this configuration the Am/=0 lines vanish. (Johnson, 1985.)...

Fig. 4. 15. Plot of hyperfine field Bhf against applied field B for CsjFeCls HjO at 5.4 K. Dots represent the data with B parallel to the magnetic easy axis and crosses represent the data obtained with B perpendicular to the magnetic easy axis. Applied fields Ba, and and B mark the phase transitions to the spin flopped and paramagnetic phases. (Johnson, 1985.)...

Fig. 4.18. Mossbauer spectra of KjFeFj at 4.2 K. The top spectrum is of a powder sample, those below are of a single crystal with the applied field along the magnetic easy axis. (Gupta et al, 1978.)...

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