The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform

S T Bramwell - One of the best experts on this subject based on the ideXlab platform.

  • Nuclear spin assisted quantum tunnelling of Magnetic Monopoles in spin ice
    Nature Communications, 2019
    Co-Authors: Carley Paulsen, S. R. Giblin, Keisuke Matsuhira, Elsa Lhotel, Ganesh Balakrishnan, Dorairaj Prabhakaran, S T Bramwell
    Abstract:

    Spin ice compounds have localised excitations that behave as Magnetic Monopoles which move by hopping from site to site, creating a chain of spins. Here the authors show that the hyperfine coupling between electron and nuclear spins is an important part of the mechanism underlying monopole motion.AbstractExtensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical Magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: Magnetic Monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the Magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with Magnetic Monopoles to resonance, allowing the Monopoles to hop and transport Magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.

  • nuclear spin assisted quantum tunnelling of Magnetic Monopoles in spin ice
    arXiv: Strongly Correlated Electrons, 2019
    Co-Authors: Carley Paulsen, Keisuke Matsuhira, Elsa Lhotel, Ganesh Balakrishnan, Dorairaj Prabhakaran, Sean Giblin, S T Bramwell
    Abstract:

    Extensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical Magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: Magnetic Monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the Magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with Magnetic Monopoles to resonance, allowing the Monopoles to hop and transport Magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.

Shivaji Lal Sondhi - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic Monopoles in spin ice
    Nature, 2008
    Co-Authors: Claudio Castelnovo, Roderich Moessner, Shivaji Lal Sondhi
    Abstract:

    We are familiar with elementary particles that carry either negative or positive electric charge, such as electrons and protons, but there is no evidence of elementary particles with a net Magnetic charge. Magnets tend to come with inseparable north and south poles, and there are no known Magnetic Monopoles despite concerted efforts to find them. But an intriguing theoretical study now proposes that Magnetic Monopoles may exist, not as elementary particles, but as emergent particles in exotic condensed matter Magnetic systems such as 'spin ice'. The theory, based on an analogy to fractional electric charges seen, for example, in quantum Hall systems in two dimensions, can explain a mysterious phase transition that has been observed experimentally in spin ice. The cover, by Alessandro Canossa, depicts a Magnetic monopole (red sphere) emerging from break-up of the dipole moment (arrows) of the underlying electronic degrees of freedom in spin ice. A theoretical study proposes that Magnetic Monopoles may appear not as elementary but as emergent particles in complex, strongly-correlated Magnetic systems such as spin ice, in analogy to fractional electric charges in quantum Hall systems. This theory explains a mysterious phase transition in spin ice that has been observed experimentally. Electrically charged particles, such as the electron, are ubiquitous. In contrast, no elementary particles with a net Magnetic charge have ever been observed, despite intensive and prolonged searches (see ref. 1 for example). We pursue an alternative strategy, namely that of realizing them not as elementary but rather as emergent particles—that is, as manifestations of the correlations present in a strongly interacting many-body system. The most prominent examples of emergent quasiparticles are the ones with fractional electric charge e/3 in quantum Hall physics2. Here we propose that Magnetic Monopoles emerge in a class of exotic magnets known collectively as spin ice3,4,5: the dipole moment of the underlying electronic degrees of freedom fractionalises into Monopoles. This would account for a mysterious phase transition observed experimentally in spin ice in a Magnetic field6,7, which is a liquid–gas transition of the Magnetic Monopoles. These Monopoles can also be detected by other means, for example, in an experiment modelled after the Stanford Magnetic monopole search8.

  • Magnetic Monopoles in Spin Ice
    Nature, 2008
    Co-Authors: Claudio Castelnovo, Roderich Moessner, Shivaji Lal Sondhi
    Abstract:

    Electrically charged particles, such as the electron, are ubiquitous. By contrast, no elementary particles with a net Magnetic charge have ever been observed, despite intensive and prolonged searches. We pursue an alternative strategy, namely that of realising them not as elementary but rather as emergent particles, i.e., as manifestations of the correlations present in a strongly interacting many-body system. The most prominent examples of emergent quasiparticles are the ones with fractional electric charge e/3 in quantum Hall physics. Here we show that Magnetic Monopoles do emerge in a class of exotic magnets known collectively as spin ice: the dipole moment of the underlying electronic degrees of freedom fractionalises into Monopoles. This enables us to account for a mysterious phase transition observed experimentally in spin ice in a Magnetic field, which is a liquid-gas transition of the Magnetic Monopoles. These Monopoles can also be detected by other means, e.g., in an experiment modelled after the celebrated Stanford Magnetic monopole search.

Carley Paulsen - One of the best experts on this subject based on the ideXlab platform.

  • Nuclear spin assisted quantum tunnelling of Magnetic Monopoles in spin ice
    Nature Communications, 2019
    Co-Authors: Carley Paulsen, S. R. Giblin, Keisuke Matsuhira, Elsa Lhotel, Ganesh Balakrishnan, Dorairaj Prabhakaran, S T Bramwell
    Abstract:

    Spin ice compounds have localised excitations that behave as Magnetic Monopoles which move by hopping from site to site, creating a chain of spins. Here the authors show that the hyperfine coupling between electron and nuclear spins is an important part of the mechanism underlying monopole motion.AbstractExtensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical Magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: Magnetic Monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the Magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with Magnetic Monopoles to resonance, allowing the Monopoles to hop and transport Magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.

  • nuclear spin assisted quantum tunnelling of Magnetic Monopoles in spin ice
    arXiv: Strongly Correlated Electrons, 2019
    Co-Authors: Carley Paulsen, Keisuke Matsuhira, Elsa Lhotel, Ganesh Balakrishnan, Dorairaj Prabhakaran, Sean Giblin, S T Bramwell
    Abstract:

    Extensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical Magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: Magnetic Monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the Magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with Magnetic Monopoles to resonance, allowing the Monopoles to hop and transport Magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.

Claudio Castelnovo - One of the best experts on this subject based on the ideXlab platform.

  • dirac strings and Magnetic Monopoles in the spin ice dy2ti2o7
    Science, 2009
    Co-Authors: David Jonathan Morris, Claudio Castelnovo, Roderich Moessner, D A Tennant, S A Grigera, B Klemke, C Czternasty
    Abstract:

    Sources of Magnetic fields-Magnetic Monopoles-have so far proven elusive as elementary particles. Condensed-matter physicists have recently proposed several scenarios of emergent quasiparticles resembling Monopoles. A particularly simple proposition pertains to spin ice on the highly frustrated pyrochlore lattice. The spin-ice state is argued to be well described by networks of aligned dipoles resembling solenoidal tubes-classical, and observable, versions of a Dirac string. Where these tubes end, the resulting defects look like Magnetic Monopoles. We demonstrated, by diffuse neutron scattering, the presence of such strings in the spin ice dysprosium titanate (Dy2Ti2O7). This is achieved by applying a symmetry-breaking Magnetic field with which we can manipulate the density and orientation of the strings. In turn, heat capacity is described by a gas of Magnetic Monopoles interacting via a Magnetic Coulomb interaction.

  • Magnetic Monopoles in spin ice
    Nature, 2008
    Co-Authors: Claudio Castelnovo, Roderich Moessner, Shivaji Lal Sondhi
    Abstract:

    We are familiar with elementary particles that carry either negative or positive electric charge, such as electrons and protons, but there is no evidence of elementary particles with a net Magnetic charge. Magnets tend to come with inseparable north and south poles, and there are no known Magnetic Monopoles despite concerted efforts to find them. But an intriguing theoretical study now proposes that Magnetic Monopoles may exist, not as elementary particles, but as emergent particles in exotic condensed matter Magnetic systems such as 'spin ice'. The theory, based on an analogy to fractional electric charges seen, for example, in quantum Hall systems in two dimensions, can explain a mysterious phase transition that has been observed experimentally in spin ice. The cover, by Alessandro Canossa, depicts a Magnetic monopole (red sphere) emerging from break-up of the dipole moment (arrows) of the underlying electronic degrees of freedom in spin ice. A theoretical study proposes that Magnetic Monopoles may appear not as elementary but as emergent particles in complex, strongly-correlated Magnetic systems such as spin ice, in analogy to fractional electric charges in quantum Hall systems. This theory explains a mysterious phase transition in spin ice that has been observed experimentally. Electrically charged particles, such as the electron, are ubiquitous. In contrast, no elementary particles with a net Magnetic charge have ever been observed, despite intensive and prolonged searches (see ref. 1 for example). We pursue an alternative strategy, namely that of realizing them not as elementary but rather as emergent particles—that is, as manifestations of the correlations present in a strongly interacting many-body system. The most prominent examples of emergent quasiparticles are the ones with fractional electric charge e/3 in quantum Hall physics2. Here we propose that Magnetic Monopoles emerge in a class of exotic magnets known collectively as spin ice3,4,5: the dipole moment of the underlying electronic degrees of freedom fractionalises into Monopoles. This would account for a mysterious phase transition observed experimentally in spin ice in a Magnetic field6,7, which is a liquid–gas transition of the Magnetic Monopoles. These Monopoles can also be detected by other means, for example, in an experiment modelled after the Stanford Magnetic monopole search8.

  • Magnetic Monopoles in Spin Ice
    Nature, 2008
    Co-Authors: Claudio Castelnovo, Roderich Moessner, Shivaji Lal Sondhi
    Abstract:

    Electrically charged particles, such as the electron, are ubiquitous. By contrast, no elementary particles with a net Magnetic charge have ever been observed, despite intensive and prolonged searches. We pursue an alternative strategy, namely that of realising them not as elementary but rather as emergent particles, i.e., as manifestations of the correlations present in a strongly interacting many-body system. The most prominent examples of emergent quasiparticles are the ones with fractional electric charge e/3 in quantum Hall physics. Here we show that Magnetic Monopoles do emerge in a class of exotic magnets known collectively as spin ice: the dipole moment of the underlying electronic degrees of freedom fractionalises into Monopoles. This enables us to account for a mysterious phase transition observed experimentally in spin ice in a Magnetic field, which is a liquid-gas transition of the Magnetic Monopoles. These Monopoles can also be detected by other means, e.g., in an experiment modelled after the celebrated Stanford Magnetic monopole search.

Keisuke Matsuhira - One of the best experts on this subject based on the ideXlab platform.

  • Nuclear spin assisted quantum tunnelling of Magnetic Monopoles in spin ice
    Nature Communications, 2019
    Co-Authors: Carley Paulsen, S. R. Giblin, Keisuke Matsuhira, Elsa Lhotel, Ganesh Balakrishnan, Dorairaj Prabhakaran, S T Bramwell
    Abstract:

    Spin ice compounds have localised excitations that behave as Magnetic Monopoles which move by hopping from site to site, creating a chain of spins. Here the authors show that the hyperfine coupling between electron and nuclear spins is an important part of the mechanism underlying monopole motion.AbstractExtensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical Magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: Magnetic Monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the Magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with Magnetic Monopoles to resonance, allowing the Monopoles to hop and transport Magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.

  • nuclear spin assisted quantum tunnelling of Magnetic Monopoles in spin ice
    arXiv: Strongly Correlated Electrons, 2019
    Co-Authors: Carley Paulsen, Keisuke Matsuhira, Elsa Lhotel, Ganesh Balakrishnan, Dorairaj Prabhakaran, Sean Giblin, S T Bramwell
    Abstract:

    Extensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical Magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: Magnetic Monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the Magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with Magnetic Monopoles to resonance, allowing the Monopoles to hop and transport Magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.

  • observation of Magnetic Monopoles in spin ice
    arXiv: Disordered Systems and Neural Networks, 2009
    Co-Authors: Hiroaki Kadowaki, Keisuke Matsuhira, Naohiro Doi, Yuji Aoki, Yoshikazu Tabata, Taku J Sato, J W Lynn, Zenji Hiroi
    Abstract:

    Excitations from a strongly frustrated system, the kagome ice state of the spin ice Dy2Ti2O7 under Magnetic fields along a [111] direction, have been studied. They are theoretically proposed to be regarded as Magnetic Monopoles. Neutron scattering measurements of spin correlations show that close to the critical point the Monopoles are fluctuating between high- and low-density states, supporting that the Magnetic Coulomb force acts between them. Specific heat measurements show that monopole-pair creation obeys an Arrhenius law, indicating that the density of Monopoles can be controlled by temperature and Magnetic field.