Uniquely in Cu 2 OSeO 3 , the Skyrmions, which are topologically protected magnetic spin vortexlike objects, display a magnetoelectric coupling and can be manipulated by externally applied electric (E) fields. Here, we explore the E-field coupling to the magnetoelectric Skyrmion lattice phase, and study the response using neutron scattering. Giant E-field induced rotations of the Skyrmion lattice are achieved that span a range of ∼25°. Supporting calculations show that an E-field-induced Skyrmion distortion lies behind the lattice rotation. Overall, we present a new approach to Skyrmion control that makes no use of spin-transfer torques due to currents of either electrons or magnons. [12,13]. All have the chiral-cubic space group P2 1 3, a weak magnetocrystalline anisotropy, and common phase diagrams with a helimagnetic ground state. Despite these similarities, the diverse transport properties lead to material specific mechanisms for Skyrmion manipulation and the associated dynamics. In the well-studied itinerant compounds, spin-transfer torques (STTs) exerted by the conduction electrons of an ultralow current density, j ≲ 10 6 A·m −2 drive the Skyrmion motion [5,[14][15][16][17][18][19]. More generally, in both MnSi and insulating Cu 2 OSeO 3 , Skyrmion lattice (SKL) rotations are observed to be driven by STTs exerted by the magnon currents induced by a thermal gradient [20]. Even though electric currents and thermal gradients have been established to generate Skyrmion motion, it remains vital to find new control mechanisms which may lead to further efficient Skyrmion-based functionalities.In the insulating SKL host compounds, the chiral lattice promotes a magnetoelectric (ME) coupling between electric (E) and magnetic orders which can be expected to lie at the heart of new Skyrmion control paradigms. The use of ME coupling for Skyrmion manipulation is also attractive for applications since losses due to Joule heating are negligible. Presently, however, open questions remain concerning the basic understanding of how an applied E field can manipulate the Skyrmion spin texture. To address this issue, we have used small-angle neutron scattering (SANS) to study the giant E-field-induced SKL rotations generated in a bulk sample of ME Cu 2 OSeO 3 . Surprisingly, the rotations saturate at an angle dependent on both the size and sign of the E field. With supporting calculations, we explain our observations, and show that an E-field-induced Skyrmion distortion leads to the observed rotations. This amounts to a new approach for Skyrmion control that does not require STTs.In Cu 2 OSeO 3 , the ME coupling exists in all magnetic phases [12,[21][22][23][24][25][26][27][28], and is generated by the d-p hybridization mechanism [12,24,29,30]. This mechanism dictates a particular ME coupling anisotropy; for a magnetic field μ 0 H∥½110 or [111], an electric polarization P emerges ∥½001 or [111], respectively [24]. In our experiments, we chose E∥½111 (which corresponds to a negative applied voltage) or ∥½111 (positive voltage). T...

Small-angle neutron scattering has been employed to study the influence of applied electric (E-)fields on the skyrmion lattice in the chiral lattice magnetoelectric Cu(2)OSeO(3). Using an experimental geometry with the E-field parallel to the [111] axis, and the magnetic field parallel to the [11(-)0] axis, we demonstrate that the effect of applying an E-field is to controllably rotate the skyrmion lattice around the magnetic field axis. Our results are an important first demonstration for a microscopic coupling between applied E-fields and the skyrmions in an insulator, and show that the general emergent properties of skyrmions may be tailored according to the properties of the host system.

We report a comprehensive study of magnetic properties of Ni 3 TeO 6 . The system crystallizes in a noncentrosymmetric rhombohedral lattice, space group R3. There are three differently coordinated Ni atoms in the unit cell. Two of them form an almost planar honeycomb lattice, while the third one is placed between the layers. Magnetization and specific heat measurements revealed a single magnetic ordering at T N = 52 K. Below T N the susceptibility with the magnetic field parallel to the c axis drops towards zero while the perpendicular susceptibility remains constant, a characteristic of antiferromagnetic materials. Neutron diffraction confirmed that the system is antiferromagnet below T N with ferromagnetic ab planes stacked antiferromagnetically along the c axis. All Ni moments are in the S = 1 spin state and point along the c axis.

NMR measurements of the (29)Si spin-lattice relaxation time T(1) were used to probe the spin-1/2 random Heisenberg chain compound BaCu(2)(Si(1-x)Ge(x))(2)O(7). Remarkable differences between the pure (x=0) and the fully random (x=0.5) cases are observed, indicating that randomness generates a distribution of local magnetic relaxations. This distribution, which is reflected in a stretched exponential NMR relaxation, exhibits a progressive broadening with decreasing temperature, caused by a growing inequivalence of magnetic sites. Compelling independent evidence for the influence of randomness is also obtained from magnetization data and Monte Carlo calculations. These results suggest the formation of random-singlet states in this class of materials, as previously predicted by theory.