Experimental evidence of noncollinear magnetism in gadolinium tetraboride (original) (raw)

Recently, the collinear or noncollinear character of the magnetic structure of gadolinium tetraboride ͑GdB 4 ͒, laying the magnetic moments in the ab plane, becomes a matter of controversy. In the present study, the observations obtained from resistivity, specific heat, and magnetic susceptibility measurements on a single crystal sample contain no evidence for a structural phase transition in this material above or below the Néel temperature T N. In addition to these measurements, the resonant x-ray Bragg diffraction structure factors derived from all the possible arrangements for Gd magnetic moments compatible with the room temperature tetragonal P4/mbm space group are calculated. The intensity derived with Shubnikov magnetic P4/mЈbЈmЈ and P4Ј / mЈbЈm space groups are found to account for the previously published resonant x-ray diffraction data on GdB 4. ͑Both Shubnikov groups have magnetoelectric symmetry.͒