† Contributed equally to this project. Magnetic monopoles 1 -3 are hypothetical elementary particles exhibiting quantized magnetic charge = ±( ) ⁄ and quantized magnetic flux = ± / . In principle, such a magnetic charge can be detected by the quantized jump in magnetic flux it generates upon passage through a superconducting quantum interference device (SQUID) 4 . Naturally, with the theoretical discovery that a plasma of emergent magnetic charges should exist in several lanthanide-pyrochlore magnetic insulators 5,6 including Dy2Ti2O7, this SQUID technique was proposed for their direct detection 6 . Experimentally, this has proven challenging because of the high number density, and the generation-recombination (GR) fluctuations, of the monopole plasma. Recently, however, theoretical advances have allowed the spectral density of magnetic-flux noise ( , ) due to GR fluctuations of ± * magnetic charge pairs to be predicted 7 , 8 . Here we report development of a SQUID based flux-noise spectrometer, and consequent measurements of the frequency and temperature dependence of ( , ) for Dy2Ti2O7 samples. Virtually all the elements of ( , )predicted for a magnetic monopole plasma, including the existence of intense magnetization noise and its characteristic frequency and temperature dependence,

Despite a well-ordered pyrochlore crystal structure and strong magnetic interactions between the Dy 3+ or Ho 3+ ions, no long range magnetic order has been detected in the pyrochlore titanates Ho2Ti2O7 and Dy2Ti2O7. To explore the actual magnetic phase formed by cooling these materials, we measure their magnetization dynamics using toroidal, boundary-free magnetization transport techniques. We find that the dynamical magnetic susceptibility of both compounds has the same distinctive phenomenology, that is indistinguishable in form from that of the dielectric permittivity of dipolar glass-forming liquids. Moreover, Ho2Ti2O7 and Dy2Ti2O7 both exhibit microscopic magnetic relaxation times that increase along the super-Arrhenius trajectories analogous to those observed in glass-forming dipolar liquids. Thus, upon cooling below about 2K, Dy2Ti2O7 and Ho2Ti2O7 both appear to enter the same magnetic state exhibiting the characteristics of a glass-forming spin-liquid. PACS numbers: 75.50.Lk, 75.47.LxA recent proposal 29 that the magnetic state of arXiv:1707.09014v3 [cond-mat.str-el]

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We theoretically study the equilibrium and dynamic properties of nanoscale magnetic tunnel junctions (MTJs) and magnetic wires, in which an electric field controls the magnetic anisotropy through spin-orbit coupling. By performing micromagnetic simulations, we construct a rich phase diagram and find that, in particular, the equilibrium magnetic textures can be tuned between Néel and Bloch domain walls in an elliptical MTJ. Furthermore, we develop a phenomenological model of a quasi-one-dimensional domain wall confined by a parabolic potential and show that, near the Néel-to-Bloch-wall transition, a pulsed electric field induces precessional domain-wall motion which can be used to reverse the chirality of a Néel wall and even depin it. This domain-wall motion controlled by electric fields, in lieu of applied current, may provide a model for ultra-low-power domain-wall memory and logic devices.

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