Improper Dyzaloshinskii spirals and metamagnetic textures - and where to look for them

Ulrich K. Rößler, IFW Dresden

Chiral magnetic textures have been theoretically predicted for systems violating criteria of the Landau theory for continuous phase transitions [1,2]. Their experimental discovery followed with a characteristic time-lag [3,4]. Proper Dzyaloshinskii spiral states, kinks or soliton lattices, and skyrmions as twisted and localized textures of a (axial) vector order-parameter-field in non-centrosymmetric magnets now are best known examples of such textures. Theoretically, more complex states may be expected in magnetism and beyond by coupling several ordering modes. I will discuss the corresponding concept of improper Dzyaloshinskii textures that can be realized near multi-criticality. The concept has led to the first observation of a metamagnetic texture in the non-centrosymmetric antiferromagnet Ca3Ru2O7 [5]. I will sketch the phenomenology of such states and present a selection of further candidate systems. Metamagnetic textures, or more generally improper textures, are mixtures of different ordering modes. They may form either extended modulated states or localized lumps, i.e. static, mostly non-topological solitons, that can condense into mesophases. In a wide class of clean magnetic crystals, where inversion symmetry is broken, a conventional magnetic long-range order could even be avoided, owing to a specific geometric frustration enforced by the twisting influence of a static background gauge field. I will conclude with some conjectures about the existence of classical chiral spin-liquid states in acentric magnets and the question of amorphous ground-states in systems without quenched disorder.

[1] I.E. Dzyaloshinskii, Sov. Phys. JETP 19, 960 (1964)

[2] A.N. Bogdanov, D.A. Yablonskii, JETP 95, 178 (1989)

[3] P. Bak, M.H. Jensen, J.Phys. C 13, L881 (1980); O.Nakanishi et al., Solid State Comm. 35, 995 (1980)

[4] S. Mühlbauer et al., Science 323, 915 (2009); X.Z. Yu et al. Nature 465, 901 (2010)

[5] D. A. Sokolov et al., Nat. Phys. 15, 671 (2019)

PDF file of the talk available here