Taro Nakajima

Large anisotropic deformation of skyrmions in strained crystal

Mechanical control of magnetism is an important and promising approach in spintronics. To date, strain control has mostly been demonstrated in ferromagnetic structures by exploiting a change in magnetocrystalline anisotropy. It would be desirable to achieve large strain effects on magnetic nanostructures. Here, using in situ Lorentz transmission electron microscopy, we demonstrate that anisotropic strain as small as 0.3% in a chiral magnet of FeGe induces very large deformations in magnetic skyrmions, as well as distortions of the skyrmion crystal lattice on the order of 20%. Skyrmions are stabilized by the Dzyaloshinskii-Moriya interaction, originating from a chiral crystal structure. Our results show that the change in the modulation of the strength of this interaction is amplified by two orders of magnitude with respect to changes in the crystal lattice due to an applied strain. Our findings may provide a mechanism to achieve strain control of topological magnetic structures based on the Dzyaloshinskii-Moriya interaction.

Uniaxial stress control of skyrmion phase

Magnetic skyrmions, swirling nanometric spin textures, have been attracting increasing attention by virtue of their potential applications for future memory technology and their emergent electromagnetism. Despite a variety of theoretical proposals oriented towards skyrmion-based electronics (that is, skyrmionics), few experiments have succeeded in creating, deleting and transferring skyrmions, and the manipulation methodologies have thus far remained limited to electric, magnetic and thermal stimuli. Here, we demonstrate a new approach for skyrmion phase control based on a mechanical stress. By continuously scanning uniaxial stress at low temperatures, we can create and annihilate a skyrmion crystal in a prototypical chiral magnet MnSi. The critical stress is merely several tens of MPa, which is easily accessible using the tip of a conventional cantilever. The present results offer a new guideline even for single skyrmion control that requires neither electric nor magnetic biases and consumes extremely little energy.

Electric polarization induced by a proper helical magnetic ordering in a delafossite multiferroic Cu Fe 1 − x Al x O 2

We have established the relationship between the electric polarization vector and the local spin arrangement including vector spin chirality in delafossite multiferroic

Spin Noncollinearlity in Multiferroic Phase of Triangular Lattice Antiferromagnet CuFe1-xAlxO2

\mathrm{Cu}{\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{\mathrm{O}}_{2}

Identification of microscopic spin-polarization coupling in the ferroelectric phase of magnetoelectric multiferroic CuFe 1 − x Al x O 2

. The results of polarized neutron diffraction and pyroelectric measurements demonstrate that proper helical magnetic ordering in

Skyrmion lattice structural transition in MnSi

\mathrm{Cu}{\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{\mathrm{O}}_{2}

Néel-Type Skyrmion Lattice in the Tetragonal Polar Magnet VOSe 2 O 5

induces a spontaneous electric polarization parallel to the vector spin chirality. This result cannot be explained by the Katsura-Nagaosa-Balatsky model, which successfully explains the ferroelectricity in recently explored ferroelectric helimagnets, such as

Control of ferroelectric polarization via uniaxial pressure in the spin-lattice-coupled multiferroic CuFe1−xGaxO2

\mathrm{Tb}\mathrm{Mn}{\mathrm{O}}_{3}

Magnetic phase diagram of multiferroic delafossite CuFe1−yGayO2

. We thus conclude that

Heat-Treatment-Induced Switching of Magnetic States in the Doped Polar Semiconductor Ge1-xMnxTe.

\mathrm{Cu}{\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{\mathrm{O}}_{2}