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  Andriushin, N.D.; Grumbach, J.; Kim, J.H.; Reehuis, M.; Tymoshenko, Y.V.; Onykiienko, Y.A.; Jain, A.; Macfarlane, W.A.; Maljuk, A.; Granovsky, S.; Hoser, A.; Pomjakushin, V.; Ollivier, J.; Doerr, M.; Keimer, B.; Inosov, D.S.; Peets, D.C.: Rich magnetic phase diagram of putative helimagnet Sr₃Fe₂O₇. Physical Review B 108 (2023), p. 174420/1-13

10.1103/physrevb.108.174420
Open Access Version

Abstract:
The cubic perovskite SrFeO3 was recently reported to host hedgehog- and skyrmion-lattice phases in a highly symmetric crystal structure which does not support the Dzyaloshinskii-Moriya interactions commonly invoked to explain such magnetic order. Hints of a complex magnetic phase diagram have also recently been found in powder samples of the single-layer Ruddlesden-Popper analog Sr2FeO4, so a reinvestigation of the bilayer material Sr3Fe2O7, believed to be a simple helimagnet, is called for. Our magnetization and dilatometry studies reveal a rich magnetic phase diagram with at least six distinct magnetically ordered phases and strong similarities to that of SrFeO3. In particular, at least one phase is apparently multiple-q, and the qs are not observed to vary among the phases. Since Sr3Fe2O7 has only two possible orientations for its propagation vector, some of the phases are likely exotic multiple-q order, and it is possible to fully detwin all phases and more readily access their exotic physics.