† 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]

We have carried out torsional oscillator experiments on solid 4He at temperatures between 1.3 K and 1.9 K. We discovered phenomena similar to those observed at temperatures below 0.2 K, which currently are under debate regarding their interpretation in terms of supersolidity. These phenomena include a partial decoupling of the solid helium mass from the oscillator, a change of the dissipation, and a velocity dependence of the decoupled mass. These were all observed both in the bcc and hcp phases of solid 4He. The onset of this behavior is coincidental with the creation of crystalline disorder but does not depend strongly on the crystalline symmetry or on the temperature.

The investigation of transport properties in normal liquid helium-3 and its topological superfluid phases provides insights into related phenomena in electron fluids, topological materials, and putative topological superconductors. It relies on the measurement of mass, heat, and spin currents, due to system neutrality. Of particular interest is transport in strongly confining channels of height approaching the superfluid coherence length, to enhance the relative contribution of surface excitations, and suppress hydrodynamic counterflow. Here we report on the thermal conduction of helium-3 in a 1.1 μm high channel. In the normal state we observe a diffusive thermal conductivity that is approximately temperature independent, consistent with interference of bulk and boundary scattering. In the superfluid, the thermal conductivity is only weakly temperature dependent, requiring detailed theoretical analysis. An anomalous thermal response is detected in the superfluid which we propose arises from the emission of a flux of surface excitations from the channel.