Condensed Matter

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12/13 PSI - Explorations in Condensed Matter Lecture 15
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 26, 2013

PIRSA:13040061
Condensed Matter
Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Pat Clancy University of Toronto
April 25, 2013

PIRSA:13040137
Condensed Matter
Higgs Boson in Condensed Matter: From Polaron to Topological Insulator
April 25, 2013

PIRSA:13040132
High Energy Physics

Condensed Matter
New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Katharina Fristsch McMaster University
April 25, 2013

PIRSA:13040136
Condensed Matter
Absence of Pauling's Residual Entropy in Dy2Ti2O

Jan Kycia University of Waterloo
April 25, 2013

PIRSA:13040130
Condensed Matter
Spin-1/2 Heisenberg Antiferromagnet on the Kagome Lattice: a Z2 Spin Liquid with Fermionic Spinons

Zhihao Hao University of Waterloo
April 25, 2013

PIRSA:13040134
Condensed Matter
Reaching Experimentally Quantum Criticality: A Playground to Explore Novel Correlated Quantum States of Matter

Radu Coldea University of Oxford
April 25, 2013

PIRSA:13040133
Condensed Matter
12/13 PSI - Explorations in Condensed Matter Lecture 14
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 25, 2013

PIRSA:13040060
Condensed Matter
Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems
April 24, 2013

PIRSA:13040116
Condensed Matter
12/13 PSI - Explorations in Condensed Matter Lecture 13
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 24, 2013

PIRSA:13040059
Condensed Matter
Quantum transport in one dimension: from integrability to many-body localization and topology

Joel Moore University of California, Berkeley
April 23, 2013

PIRSA:13040125
Condensed Matter
12/13 PSI - Explorations in Condensed Matter Lecture 12
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 23, 2013

PIRSA:13040058
Condensed Matter

12/13 PSI - Explorations in Condensed Matter Lecture 15
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 26, 2013

PIRSA:13040061
Condensed Matter
Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Pat Clancy University of Toronto
April 25, 2013

PIRSA:13040137
Condensed Matter
The physics of iridium-based 5d transition metal oxides has attracted significant interest due to the potential for exotic magnetic and electronic ground states driven by strong spin-orbit coupling effects. Among the most extensively studied iridates is the layered perovskite Sr2IrO4, which was recently proposed as the first experimental realization of a novel Jeff=1/2 spin-orbital Mott insulating state. Intriguing similarities between Sr2IrO4 and La2CuO4, the parent compound of the high-Tc cuprates, have also led to speculation that it may be possible to induce superconductivity in this system through chemical doping. We have investigated the magnetic properties of the doped system Sr2Ir1-xRhxO4 using a combination of resonant magnetic x-ray scattering (RMXS), resonant inelastic x-ray scattering (RIXS), and x-ray absorption spectroscopy (XAS) techniques. These measurements reveal the effect of Rh-doping on the magnetic structure, phase diagram, and characteristic magnetic excitations of Sr2IrO4, and provide fundamental information about the role of quenched Rh impurities.
Higgs Boson in Condensed Matter: From Polaron to Topological Insulator
April 25, 2013

PIRSA:13040132
High Energy Physics

Condensed Matter
In this talk I will briefly review the polaron physics, which has helped theorists to conceive the BCS theory of conventional superconductors as well as experimentalists to discover high temperature superconductors in the cuprates. Specifically I will talk about how charge carriers obtain their
masses from coupling to the phonon field in one, two, three or higher dimensions. More recently, there is increasing interest in topological insulators where a gap can be opened which may suggest new version of Higgs mechanism in condensed matter.
New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Katharina Fristsch McMaster University
April 25, 2013

PIRSA:13040136
Condensed Matter
The ground state of the candidate spin liquid pyrochlore magnet Tb2Ti2O7 (TTO) has been long debated. Despite theoretical expectations of magnetic order below ~1K based on classical Ising-like Tb3+ spins, earlier muSR and neutron scattering experiments showed no long range order down to 50mK. This motivated two theoretical scenarios to account for the apparently disordered ground state: a quantum spin ice scenario and a non-magnetic singlet ground state. I will discuss new neutron scattering measurements on TTO that show short range spin correlations developing below ~ 0.5 K with a (½, ½, ½) ordering wavevector, and a concomitant opening of a spin gap across most of the Brillouin zone. Our measurements also refine the crystal field ground state for Tb3+ in TTO and in its sister, “soft” spin ice compound Tb2Sn2O7.
Absence of Pauling's Residual Entropy in Dy2Ti2O

Jan Kycia University of Waterloo
April 25, 2013

PIRSA:13040130
Condensed Matter
The discovery of the spin-ice phase in Dy2Ti2O7 numbers among the most significant findings in magnetic materials in over a decade. The spin-ice model is based on an elegant analogy to Pauling’s model of geometrical frustration in water ice, and predicts the same residual entropy, as confirmed by numerous measurements. Melko, den Hertog and Gingras, with numerical work using a loop algorithm to speed up equilibration times, were able to determine an ordering for this system. This had not been seen experimentally observed by several groups. I will present new experimental results for the specific heat of Dy2Ti2O7, demonstrating why previous measurements were unable to correctly capture its low temperature behaviour. By carefully tracking the flow of heat into and out of the material, we observe a non-vanishing specific heat at low temperatures indicating the residual entropy does not actually agree with the Pauling value.
Spin-1/2 Heisenberg Antiferromagnet on the Kagome Lattice: a Z2 Spin Liquid with Fermionic Spinons

Zhihao Hao University of Waterloo
April 25, 2013

PIRSA:13040134
Condensed Matter
Motivated by recent numerical and experimental studies of the spin-1/2 Heisenberg antiferromagnet on kagome, we formulate a many-body model for fermionic spinons, which are just uncoupled spins. The spinons interact with an emergent U(1) gauge field and experience strong short-range attraction in the S=0 channel. The ground state of the model is generically a Z(2) liquid. We calculate the edge of the two-spinon continuum and compare the theory to the slave-fermion approach to the Heisenberg model.
Reaching Experimentally Quantum Criticality: A Playground to Explore Novel Correlated Quantum States of Matter

Radu Coldea University of Oxford
April 25, 2013

PIRSA:13040133
Condensed Matter
Realizing experimentally continuous phase transitions in the electronic ground state of materials near zero temperature as a function of tuning some external parameter (magnetic field, pressure etc.) offers a unique opportunity to probe the extreme regime (near the transition point) where strong quantum correlations encompass the macroscopic sample as a whole, so called “quantum criticality” [1]. In this regime of strong correlations small perturbations/interactions can stabilize novel forms order or collective fluctuations that otherwise do not exist. One of the theoretically most studied paradigms for quantum criticality is a chain of Ising spins driven by a transverse field to a critical point separating spontaneous magnetic order and paramagnetic phases. We have realized this system experimentally by applying strong magnetic fields to the quasi-one-dimensional Ising ferromagnet CoNb2O6 and have probed via single-crystal inelastic neutron scattering the evolution of the magnetic order and spin excitation spectrum as a function of applied field at mili-Kelvin temperatures [2]. Near the critical point the spin excitations were theoretically predicted nearly two decades ago to have a set of quantum resonances (collective modes of vibration of the interacting spins) with universal ratios between their frequencies reflecting an exceptional mathematical structure of the quantum many-body eigenstates with a “hidden” E8 symmetry governing the physics in the scaling limit. Experiments indeed observed evidence for a spectrum of resonances and the ratio between the frequencies of the two lowest modes approached the "golden ratio" near the critical point, as predicted by field theory. As a second example of novel physics near quantum criticality I will discuss how an amplitude-modulated incommensurate spin-density wave (SDW) order appears near the field-induced critical point in the quasi-1D spin-1/2 XY antiferromagnet Cs2CoCl4. Incommensurate SDWs are very uncommon in magnetic insulators and are not stable zero-temperature ground states at the classical mean-field level, we propose that here such a state is stabilized by the strong quantum fluctuations associated with the proximity to the critical point and the weak frustrated inter-chain couplings.
12/13 PSI - Explorations in Condensed Matter Lecture 14
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 25, 2013

PIRSA:13040060
Condensed Matter
Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems
April 24, 2013

PIRSA:13040116
Condensed Matter
In one extreme, where the interactions are sufficiently weak compared to the interactions, electrons form a “Fermi liquid” – the state that accounts for the properties of simple metals. In the other extreme, where the interactions are dominant, the electrons form various “Mott” insulating or “Wigner crystalline” phases, often characterized by broken spatial and/or magnetic symmetries. Corresponding charge and/or magnetically ordered insulating phases are common in nature. Between these two extremes lie highly correlated electronic fluids, and correspondingly a host of interesting and perplexing materials, including such diverse systems as the cuprate and iron-based high temperature superconductors, the failed metamagnet Sr3Ru2O7, and a variety of quantum Hall fluids. Some insight into electron fluids in this rich intermediate coupling regime can be obtained from viewing them as partially melted electron solids, rather than as strongly interacting gases. Here, analogies with the liquid crystalline phases of complex classical fluids provide useful guidance for a new approach to this key problem in condensed matter physics.
12/13 PSI - Explorations in Condensed Matter Lecture 13
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 24, 2013

PIRSA:13040059
Condensed Matter
Quantum transport in one dimension: from integrability to many-body localization and topology

Joel Moore University of California, Berkeley
April 23, 2013

PIRSA:13040125
Condensed Matter
Recent advances in analytical theory and numerical methods enable some long-standing questions about transport in one dimension to be answered; these questions are closely related to transport experiments in quasi-1D compounds. The spinless fermion chain with nearest-neighbor interactions at half-filling, or equivalently the XXZ model in zero magnetic field, is an example of an integrable system in which no conventional conserved quantity forces dissipationless transport (Drude weight); we show that there is nevertheless a Drude weight and that at some points its contribution is from a new type of conserved quantity recently constructed by Prosen. Adding an integrability-breaking perturbation leads to a scaling theory of conductivity at low temperature. Adding disorder, we study the question of how Anderson localization is modified by interactions when the system remains fully quantum coherent ("many-body localization"). We find that even weak interactions are a singular perturbation on some quantities: entanglement grows slowly but without limit, suggesting that dynamics in the possible many-body localized phase are glass-like. If time permits, some results on the fractional Luttinger's theorem and the 1D limit of quantum Hall states will be presented.
12/13 PSI - Explorations in Condensed Matter Lecture 12
- Guifre Vidal Alphabet (United States)
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
April 23, 2013

PIRSA:13040058
Condensed Matter

Title	Speaker(s)	Date	Talk Type	Info link
12/13 PSI - Explorations in Condensed Matter Lecture 15	Guifre Vidal, Xiao-Gang Wen	2013-04-26	Course	View details
Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4	Pat Clancy	2013-04-25	Conference	View details
Higgs Boson in Condensed Matter: From Polaron to Topological Insulator		2013-04-25	Conference	View details
New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7	Katharina Fristsch	2013-04-25	Conference	View details
Absence of Pauling's Residual Entropy in Dy2Ti2O	Jan Kycia	2013-04-25	Conference	View details
Spin-1/2 Heisenberg Antiferromagnet on the Kagome Lattice: a Z2 Spin Liquid with Fermionic Spinons	Zhihao Hao	2013-04-25	Conference	View details
Reaching Experimentally Quantum Criticality: A Playground to Explore Novel Correlated Quantum States of Matter	Radu Coldea	2013-04-25	Conference	View details
12/13 PSI - Explorations in Condensed Matter Lecture 14	Guifre Vidal, Xiao-Gang Wen	2013-04-25	Course	View details
Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems		2013-04-24	Scientific Series	View details
12/13 PSI - Explorations in Condensed Matter Lecture 13	Guifre Vidal, Xiao-Gang Wen	2013-04-24	Course	View details
Quantum transport in one dimension: from integrability to many-body localization and topology	Joel Moore	2013-04-23	Scientific Series	View details
12/13 PSI - Explorations in Condensed Matter Lecture 12	Guifre Vidal, Xiao-Gang Wen	2013-04-23	Course	View details

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12/13 PSI - Explorations in Condensed Matter Lecture 15

Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Higgs Boson in Condensed Matter: From Polaron to Topological Insulator

New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Absence of Pauling's Residual Entropy in Dy2Ti2O

Spin-1/2 Heisenberg Antiferromagnet on the Kagome Lattice: a Z2 Spin Liquid with Fermionic Spinons

Reaching Experimentally Quantum Criticality: A Playground to Explore Novel Correlated Quantum States of Matter

12/13 PSI - Explorations in Condensed Matter Lecture 14

Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems

12/13 PSI - Explorations in Condensed Matter Lecture 13

Quantum transport in one dimension: from integrability to many-body localization and topology

12/13 PSI - Explorations in Condensed Matter Lecture 12

12/13 PSI - Explorations in Condensed Matter Lecture 15

Diluted Magnetism in Iridates: Studies of Rh-doped Sr2Ir2O4

Higgs Boson in Condensed Matter: From Polaron to Topological Insulator

New Neutron Scattering Results on the Enigmatic Ground State of the Pyrochlore Magnet Tb2Ti2O7

Absence of Pauling's Residual Entropy in Dy2Ti2O

Spin-1/2 Heisenberg Antiferromagnet on the Kagome Lattice: a Z2 Spin Liquid with Fermionic Spinons

Reaching Experimentally Quantum Criticality: A Playground to Explore Novel Correlated Quantum States of Matter

12/13 PSI - Explorations in Condensed Matter Lecture 14

Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems

12/13 PSI - Explorations in Condensed Matter Lecture 13

Quantum transport in one dimension: from integrability to many-body localization and topology

12/13 PSI - Explorations in Condensed Matter Lecture 12