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MA: Fachverband Magnetismus

MA 18: Spin Structures and Magnetic Phase Transitions

MA 18.8: Vortrag

Mittwoch, 25. März 2009, 12:00–12:15, HSZ 401

Skyrmion textures in uniaxially distorted cubic helimagnets — •U.K. Rößler¹, A.B. Butenko^1,2, A.A. Leonov^1,2, and A.N. Bogdanov¹ — ¹IFW Dresden — ²Donetsk Inst. for Physics & Technology

In magnetic systems with intrinsic or induced chirality localized and modulated multidimensional structures “Skyrmions” have been predicted to exist as metastable or thermodynamically stable states [1,2]. We show that in cubic helimagnets, as the intermetallic compounds MnSi, FeGe with B20-structure, uniaxial distortions stabilize Skyrmion lattices in a broad range of magnetic fields. Using a phenomenological theory for modulated and localized states in noncentrosymmetric magnetic crystals, the equilibrium parameters of the vortices, helices, and cycloids are determined in dependence on magnetic field and the uniaxial anisotropy induced, e.g., by uniaxial strains. Magnetic phase diagrams hold existence regions for different modulated and homogeneous phases. In particular, multiply modulated Skyrmionic textures are stabilized by an external field similar to the states described earlier for uniaxial crystals [3]. We argue that Skyrmion states could be stabilized in thin layers of cubic helimagnets or ordinary ferromagnets by applying uniaxial stresses. The formation of Skyrmion lattices is determined by the balance of energy gains through double-twist structures in the core and the tails of vortex states. — [1] A.N. Bogdanov, U.K.Rößler, Phys. Rev. Lett. 87, 037203 (2001). [2] U.K.Rößler, A.N.Bogdanov, C.Pfleiderer, Nature (London) 442, 797 (2007). [3] A.N. Bogdanov, D.A. Yablonskii, Sov. Phys. JETP 68 101 (1989).