Magnetic Monopole Noise

Abstract

Magnetic monopoles are hypothetical elementary particles exhibiting quantized magnetic charge $m_0=\pm (h/{\mu }_{0}e)$ and quantized magnetic flux ${\Phi }_0=\pm h/e$. A classic proposal for detecting such magnetic charges is to measure the quantized jump in magnetic flux $\Phi$ threading the loop of a superconducting quantum interference device (SQUID) when a monopole passes through it. Naturally, with the theoretical discovery that a plasma of emergent magnetic charges should exist in several lanthanide-pyrochlore magnetic insulators, including Dy${}_2$Ti${}_2$O${}_7$, this SQUID technique was proposed for their direct detection. Experimentally, this has proven extremely 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 $S_{\Phi }(\omega ,T)$ due to GR fluctuations of $\pm m_{\ast }$ magnetic charge pairs to be determined. These theories present a sequence of strikingly clear predictions for the magnetic-flux noise signature of emergent magnetic monopoles. Here we report development of a high-sensitivity, SQUID based flux-noise spectrometer, and consequent measurements of the frequency and temperature dependence of $S_{\Phi }(\omega ,T)$ for Dy${}_2$Ti${}_2$O${}_7$ samples. Virtually all the elements of $S_{\Phi }(\omega ,T)$ predicted for a magnetic monopole plasma, including the existence of intense magnetization noise and its characteristic frequency and temperature dependence, are detected directly. Moreover, comparisons of simulated and measured correlation functions $C_{\Phi }(t)$ of the magnetic-flux noise $\Phi (t)$ imply that the motion of magnetic charges is strongly correlated because traversal of the same trajectory by two magnetic charges of same sign is forbidden.

References in corpus (19)

• Magnetic Monopoles in Spin Ice
• Dirac Strings and Magnetic Monopoles in Spin Ice Dy2Ti2O7
• Dipolar Interactions and Origin of Spin Ice in Ising Pyrochlore Magnets
• Magnetic Charge Transport
• Spin Ice, Fractionalization and Topological Order
• Low Temperature Spin Freezing in Dy2Ti2O7 Spin Ice
• Thermodynamic Properties of the Dipolar Spin Ice Model
• Magnetic Monopole Dynamics in Spin Ice
• Spin Dynamics at Very Low Temperature in Spin Ice Dy${}_2$Ti${}_2$O${}_7$
• Brownian Motion and Quantum Dynamics of Magnetic Monopoles in Spin Ice
• Neutron Scattering Investigation of the Spin Ice State in Dy2Ti2O7
• Observation of Spin Glass Dynamics in Dilute LiHo${}_x$Y${}_{1-x}$F${}_4$
• A Supercooled Spin Liquid State in the Frustrated Pyrochlore Dy2Ti2O7
• Experimental signature of the attractive Coulomb force between positive and negative magnetic monopoles in spin ice
• Emergent Electrochemistry in Spin Ice: Debye-Hückel Theory and Beyond
• Proposal for the Detection of Magnetic Monopoles in Spin Ice via Nanoscale Magnetometry
• AC Wien effect in spin ice, manifest in non-linear non-equilibrium susceptibility
• Common Glass-Forming Spin-Liquid State in the Pyrochlore Magnets Dy${}_2$Ti${}_2$O${}_7$ and Ho${}_2$Ti${}_2$O${}_7$
• AC Susceptibility of the Dipolar Spin Ice Dy2Ti2O7: Experiments and Monte Carlo Simulations

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• Experimental signatures of quantum and topological states in frustrated magnetism
• Dynamical fractal and anomalous noise in a clean magnetic crystal
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• Search of spin-dependent fifth forces with precision magnetometry
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• Searches for exotic spin-dependent interactions with spin sensors
• Anomalous Magnetoresistance by Breaking Ice Rule in Bi2Ir2O7/Dy2Ti2O7 Heterostructure
• The Colored Noise of Magnetic Monopoles: Subdiffusion in a Coevolving Vacuum and Spin Ice Exponents
• Fragmented spin ice and multi-$k$ ordering in rare-earth antiperovskites
• Magnetic-Field-Dependent Thermodynamic Properties of Square and Quadrupolar Artificial Spin Ice
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• Violation of the fluctuation-dissipation theorem and effective temperatures in spin ice
• The Concept of Spin Ice Graphs and a Field Theory for their Topological Monopoles and Charges
• Dichotomous Dynamics of Magnetic Monopole Fluids
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• [111]-strained spin ice: Localization of thermodynamically deconfined monopoles
• Spin ice in a general applied magnetic field: Kasteleyn transition, magnetic torque and rotational magnetocaloric effect
• Thermodynamics and fractal dynamics of nematic spin ice, a doubly frustrated pyrochlore Ising magnet
• Exact Continuum Representation of Long-range Interacting Systems and Emerging Exotic Phases in Unconventional Superconductors
• Spin dynamics of the director state in frustrated hyperkagome systems
• Deconstructing Magnetization Noise: Degeneracies, Phases, and Mobile Fractionalized Excitations in Tetris Artificial Spin Ice
• The Future of the Correlated Electron Problem
• Power spectrum of magnetic relaxation in spin ice: anomalous diffusion in a Coulomb fluid
• Thermal Conductivity of Square Ice
• Gauge-Free Duality in Pure Square Spin Ice: Topological Currents and Monopoles
• Exploring possible magnetic monopoles-induced magneto-electricity in spin ices
• Scaling study of diffusion in dynamic crowded spaces
• Complex field reversal dynamics in nanomagnetic systems
• Random Transverse Field Effects on Magnetic Noise in Spin Systems
• Spinon mediation of witness spin dynamics in herbertsmithite
• Hearing the light: stray-field noise from the emergent photon in quantum spin ice