fig4

Figure 4. Direct visualization of the AF order in insulating antiferromagnets. (A) SHG imaging of the antiferromagnetic state of a NiO crystal and the SHG intensity angular dependences corresponding to the various antiferromagnetic S domains, top panel reprinted with permission from Fiebig et al. Copyright 2001 by the American Physical Society^[46]. The lower panel reprinted with permission from Sänger et al. Copyright 2006 by the American Physical Society^[47]. (B) SHG imaging of 180° antiferromagnetic domains in a Cr₂O₃ crystal and the dependence in energy of the SHG intensity presenting the large circular dichroism at resonance, which leads to the SHG antiferromagnetic contrast. Top panel reprinted with permission of AIP Publishing from Fiebig et al. and lower panel reprinted with permission from Fiebig et al. Copyright 1994 by the American Physical Society^[48,49].