Mark Lumsden - Academia.edu (original) (raw)

Papers by Mark Lumsden

Research paper thumbnail of Magnons , fractional excitations , and field-induced transitions in α-RuCl 3

Christian Balz, ∗ Paula Lampen-Kelley, 3 Arnab Banerjee, Jiaqiang Yan, Zhilun Lu, Xinzhe Hu, Swap... more Christian Balz, ∗ Paula Lampen-Kelley, 3 Arnab Banerjee, Jiaqiang Yan, Zhilun Lu, Xinzhe Hu, Swapnil M. Yadav, Yasu Takano, Yaohua Liu, David A. Tennant, Mark D. Lumsden, David Mandrus, 3 and Stephen E. Nagler Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany Department of Physics, University of Florida, Gainesville, Florida 32611, USA (Dated: March 15, 2019)

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Research paper thumbnail of Frustration-induced spin wave anomaly and dimension instability in <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi mathvariant="normal">F</mi><mi mathvariant="normal">e</mi><mi mathvariant="normal">G</mi><msub><mi mathvariant="normal">e</mi><mn>2</mn></msub></mrow><annotation encoding="application/x-tex">\rm FeGe_2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8333em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathrm">FeG</span><span class="mord"><span class="mord mathrm">e</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathrm mtight">2</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span></span>

Inelastic neutron scattering was used to probe the spin dynamics of the long-range magnetic struc... more Inelastic neutron scattering was used to probe the spin dynamics of the long-range magnetic structure of single crystal FeGe2. An unusual checkerboard-shaped anomaly located far from the magnetic satellite peaks of the incommensurate order was found in the magnetic dynamical structure factor. Using expanded ranges of wave-vector and energy transfer, we are able to develop a new model Hamiltonian that includes a heretofore unconsidered intraplane next-nearest neighbor interaction. The checkerboard-shaped anomaly is attributed to the near-perfect magnetic frustration in FeGe2, which also facilitates the emergence of unexpected two-dimension magnetic order in the system.

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Research paper thumbnail of The ground state of a quantum critical system

arXiv: Strongly Correlated Electrons, 2006

The competition between the tendency of magnetic moments to order at low temperatures, and the te... more The competition between the tendency of magnetic moments to order at low temperatures, and the tendency of conduction electrons to shield these moments, can result in a phase transition that takes place at zero Kelvin, the quantum critical point (QCP). So far, the ground state of these types of systems has remained unresolved. We present neutron scattering experiments that show that the ground state of a sample representative of a class of QCP-systems is determined by the residual interactions between the conduction electrons, resulting in a state with incommensurate intermediate-range order. However, long-range order is thwarted by quantum fluctuations that locally destroy magnetic moments, leaving the system with too few moments to achieve long-range order.

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Research paper thumbnail of Behavior of the breathing pyrochlore lattice Ba3Yb2Zn5O11 in applied magnetic field

Journal of Physics: Condensed Matter, 2018

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Research paper thumbnail of Spin-liquid polymorphism in a correlated electron system on the threshold of superconductivity

Proceedings of the National Academy of Sciences, 2015

Significance Liquid polymorphism and liquid–liquid phase transformations are remarkable phenomena... more Significance Liquid polymorphism and liquid–liquid phase transformations are remarkable phenomena of great fundamental and practical interest, as is unconventional superconductivity. Yet, despite being intensely studied, they still remain enigmatic. Our results not only provide a rare experimental example of liquid polymorphism, which occurs in the spin system of an iron chalcogenide superconductor, but also establish its unexpected connection with the onset of unconventional superconductivity.

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Research paper thumbnail of Ground state of a quantum critical system: Neutron scattering onCe(Ru1−xFex)2Ge2

Physical Review B, 2007

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Research paper thumbnail of Weak Ferromagnetism and Field-Induced Spin Reorientation inK2V3O8

Physical Review Letters, 2001

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Research paper thumbnail of Quasi-One-Dimensional Magnons in an Intermetallic Marcasite

Physical Review Letters, 2012

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Research paper thumbnail of Charge Order inLuFe2O4: Antiferroelectric Ground State and Coupling to Magnetism

Physical Review Letters, 2008

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Research paper thumbnail of Magnetic Field Enhancement of Heat Transport in the 2D Heisenberg AntiferromagnetK2V3O8

Physical Review Letters, 2002

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Research paper thumbnail of Ferro-Orbital Ordering Transition in Iron Telluride Fe1+yTe

Physical Review Letters, 2014

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Research paper thumbnail of Three-Dimensional Magnetic Correlations in MultiferroicLuFe2O4

Physical Review Letters, 2008

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Research paper thumbnail of Antiferromagnetic order and superlattice structure in nonsuperconducting and superconducting RbyFe1.6+xSe2

Physical Review B, 2011

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Research paper thumbnail of Paramagnetic spin correlations inCaFe2As2single crystals

Physical Review B, 2010

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Research paper thumbnail of Phase transitions in LaFeAsO: Structural, magnetic, elastic, and transport properties, heat capacity and Mössbauer spectra

Physical Review B, 2008

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Research paper thumbnail of Temperature-dependent bilayer ferromagnetism inSr3Ru2O7

Physical Review B, 2006

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Research paper thumbnail of Neutron scattering studies of spin excitations in superconducting Rb0.82Fe1.68Se2

Physical Review B, 2012

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Research paper thumbnail of Competing magnetic ground states in nonsuperconducting Ba(Fe1−xCrx)2As2as seen via neutron diffraction

Physical Review B, 2011

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Research paper thumbnail of Temperature dependence of the resonance and low-energy spin excitations in superconducting FeTe0.6Se0.4

Physical Review B, 2012

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Research paper thumbnail of Effect of pressure on the neutron spin resonance in the unconventional superconductor FeTe_{0.6}Se_{0.4}

Physical Review B, 2012

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Research paper thumbnail of Magnons , fractional excitations , and field-induced transitions in α-RuCl 3

Christian Balz, ∗ Paula Lampen-Kelley, 3 Arnab Banerjee, Jiaqiang Yan, Zhilun Lu, Xinzhe Hu, Swap... more Christian Balz, ∗ Paula Lampen-Kelley, 3 Arnab Banerjee, Jiaqiang Yan, Zhilun Lu, Xinzhe Hu, Swapnil M. Yadav, Yasu Takano, Yaohua Liu, David A. Tennant, Mark D. Lumsden, David Mandrus, 3 and Stephen E. Nagler Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany Department of Physics, University of Florida, Gainesville, Florida 32611, USA (Dated: March 15, 2019)

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Research paper thumbnail of Frustration-induced spin wave anomaly and dimension instability in <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi mathvariant="normal">F</mi><mi mathvariant="normal">e</mi><mi mathvariant="normal">G</mi><msub><mi mathvariant="normal">e</mi><mn>2</mn></msub></mrow><annotation encoding="application/x-tex">\rm FeGe_2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8333em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathrm">FeG</span><span class="mord"><span class="mord mathrm">e</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3011em;"><span style="top:-2.55em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathrm mtight">2</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span></span>

Inelastic neutron scattering was used to probe the spin dynamics of the long-range magnetic struc... more Inelastic neutron scattering was used to probe the spin dynamics of the long-range magnetic structure of single crystal FeGe2. An unusual checkerboard-shaped anomaly located far from the magnetic satellite peaks of the incommensurate order was found in the magnetic dynamical structure factor. Using expanded ranges of wave-vector and energy transfer, we are able to develop a new model Hamiltonian that includes a heretofore unconsidered intraplane next-nearest neighbor interaction. The checkerboard-shaped anomaly is attributed to the near-perfect magnetic frustration in FeGe2, which also facilitates the emergence of unexpected two-dimension magnetic order in the system.

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Research paper thumbnail of The ground state of a quantum critical system

arXiv: Strongly Correlated Electrons, 2006

The competition between the tendency of magnetic moments to order at low temperatures, and the te... more The competition between the tendency of magnetic moments to order at low temperatures, and the tendency of conduction electrons to shield these moments, can result in a phase transition that takes place at zero Kelvin, the quantum critical point (QCP). So far, the ground state of these types of systems has remained unresolved. We present neutron scattering experiments that show that the ground state of a sample representative of a class of QCP-systems is determined by the residual interactions between the conduction electrons, resulting in a state with incommensurate intermediate-range order. However, long-range order is thwarted by quantum fluctuations that locally destroy magnetic moments, leaving the system with too few moments to achieve long-range order.

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Research paper thumbnail of Behavior of the breathing pyrochlore lattice Ba3Yb2Zn5O11 in applied magnetic field

Journal of Physics: Condensed Matter, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Spin-liquid polymorphism in a correlated electron system on the threshold of superconductivity

Proceedings of the National Academy of Sciences, 2015

Significance Liquid polymorphism and liquid–liquid phase transformations are remarkable phenomena... more Significance Liquid polymorphism and liquid–liquid phase transformations are remarkable phenomena of great fundamental and practical interest, as is unconventional superconductivity. Yet, despite being intensely studied, they still remain enigmatic. Our results not only provide a rare experimental example of liquid polymorphism, which occurs in the spin system of an iron chalcogenide superconductor, but also establish its unexpected connection with the onset of unconventional superconductivity.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Ground state of a quantum critical system: Neutron scattering onCe(Ru1−xFex)2Ge2

Physical Review B, 2007

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Research paper thumbnail of Weak Ferromagnetism and Field-Induced Spin Reorientation inK2V3O8

Physical Review Letters, 2001

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Research paper thumbnail of Quasi-One-Dimensional Magnons in an Intermetallic Marcasite

Physical Review Letters, 2012

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Research paper thumbnail of Charge Order inLuFe2O4: Antiferroelectric Ground State and Coupling to Magnetism

Physical Review Letters, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Magnetic Field Enhancement of Heat Transport in the 2D Heisenberg AntiferromagnetK2V3O8

Physical Review Letters, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Ferro-Orbital Ordering Transition in Iron Telluride Fe1+yTe

Physical Review Letters, 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Three-Dimensional Magnetic Correlations in MultiferroicLuFe2O4

Physical Review Letters, 2008

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Research paper thumbnail of Antiferromagnetic order and superlattice structure in nonsuperconducting and superconducting RbyFe1.6+xSe2

Physical Review B, 2011

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Research paper thumbnail of Paramagnetic spin correlations inCaFe2As2single crystals

Physical Review B, 2010

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Research paper thumbnail of Phase transitions in LaFeAsO: Structural, magnetic, elastic, and transport properties, heat capacity and Mössbauer spectra

Physical Review B, 2008

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Research paper thumbnail of Temperature-dependent bilayer ferromagnetism inSr3Ru2O7

Physical Review B, 2006

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Research paper thumbnail of Neutron scattering studies of spin excitations in superconducting Rb0.82Fe1.68Se2

Physical Review B, 2012

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Research paper thumbnail of Competing magnetic ground states in nonsuperconducting Ba(Fe1−xCrx)2As2as seen via neutron diffraction

Physical Review B, 2011

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Research paper thumbnail of Temperature dependence of the resonance and low-energy spin excitations in superconducting FeTe0.6Se0.4

Physical Review B, 2012

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Research paper thumbnail of Effect of pressure on the neutron spin resonance in the unconventional superconductor FeTe_{0.6}Se_{0.4}

Physical Review B, 2012

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