scholarly journals Spin liquid mediated RKKY interaction

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Henry F. Legg ◽  
Bernd Braunecker
Keyword(s):  
Wave Theory ◽  
Spin Liquid ◽  
Spin Liquids ◽  
Rkky Interaction ◽  
Nuclear Spins ◽  
Zero Energy ◽  
Small Magnetic Field ◽  
Fermionic Systems ◽  
Type Interaction ◽  
Magnon Spectrum

AbstractWe propose an RKKY-type interaction that is mediated by a spin liquid. If a spin liquid exists such an interaction could leave a fingerprint by ordering underlying localised moments such as nuclear spins. This interaction has a unique phenomenology that is distinct from the RKKY interaction found in fermionic systems; most notably the lack of a Fermi surface and absence of the requirement for itinerant electrons, since most spin liquids are insulators. We demonstrate that the interaction is predominately shaped by the lattice symmetries of the underlying spin liquid. As a working example we investigate the possible ordering of nuclear spins that interact through an underlying lattice of the two-dimensional spin-1/2 kagome antiferromagnet (KHAF), although the treatment remains general and can be extended to other spin liquids and dimensions. We find that several different nuclear spin orderings minimise the RKKY-type energy induced by the KHAF but are unstable due to a zero-energy flat magnon band in linear spin-wave theory. Despite this we show that a small magnetic field is able to gap out this magnon spectrum resulting in an intricate nuclear magnetism.

scholarly journals Correlation holes and slow dynamics induced by fractional statistics in gapped quantum spin liquids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Oliver Hart ◽  
Yuan Wan ◽  
Claudio Castelnovo
Keyword(s):  
Transport Properties ◽  
Realistic Model ◽  
Feedback Mechanism ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Spin Liquids ◽  
Slow Dynamics ◽  
Temperature Dependent ◽  
Quantum Spin Liquids ◽  
Quantum Spin Liquid

AbstractRealistic model Hamiltonians for quantum spin liquids frequently exhibit a large separation of energy scales between their elementary excitations. At intermediate, experimentally relevant temperatures, some excitations are sparse and hop coherently, whereas others are thermally incoherent and dense. Here, we study the interplay of two such species of quasiparticle, dubbed spinons and visons, which are subject to nontrivial mutual statistics – one of the hallmarks of quantum spin liquid behaviour. Our results for $${{\mathbb{Z}}}_{2}$$ Z 2 quantum spin liquids show an intriguing feedback mechanism, akin to the Nagaoka effect, whereby spinons become localised on temperature-dependent patches of expelled visons. This phenomenon has important consequences for the thermodynamic and transport properties of the system, as well as for its response to quenches in temperature. We argue that these effects can be measured in experiments and may provide viable avenues for obtaining signatures of quantum spin liquid behaviour.

scholarly journals Dichotomy in temporal and thermal spin correlations observed in the breathing pyrochlore LiGa1−xInxCr4O8

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Lee ◽  
S.-H. Do ◽  
W. Lee ◽  
Y. S. Choi ◽  
J. van Tol ◽  
...  
Keyword(s):  
Time Scale ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Fast Time ◽  
Spin Liquids ◽  
Magnetic Ground State ◽  
Spin Correlations ◽  
Magnetic Specific Heat

AbstractA breathing pyrochlore system is predicted to host a variety of quantum spin liquids. Despite tremendous experimental and theoretical efforts, such sought-after states remain elusive as perturbation terms and lattice distortions lead to magnetic order. Here, we utilize bond alternation and disorder to tune a magnetic ground state in the Cr-based breathing pyrochlore LiGa1−xInxCr4O8. By combining thermodynamic and magnetic resonance techniques, we provide experimental signatures of a spin-liquid-like state in x = 0.8, namely, a nearly T2-dependent magnetic specific heat and persistent spin dynamics by muon spin relaxation (μSR). Moreover, 7Li NMR, ZF-μSR, and ESR unveil the temporal and thermal dichotomy of spin correlations: a tetramer singlet on a slow time scale vs. a spin-liquid-like state on a fast time scale. Our results showcase that a bond disorder in the breathing pyrochlore offers a promising route to disclose exotic magnetic phases.

scholarly journals Entanglement signatures of emergent Dirac fermions: Kagome spin liquid and quantum criticality

2018 ◽  
Vol 4 (11) ◽  
pp. eaat5535 ◽  
Author(s):  
Wei Zhu ◽  
Xiao Chen ◽  
Yin-Chen He ◽  
William Witczak-Krempa
Keyword(s):  
Entanglement Entropy ◽  
Quantum Critical Point ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Dirac Fermions ◽  
Spin Liquids ◽  
Density Matrix Renormalization ◽  
Dirac Semimetal ◽  
A Charge ◽  
Aharonov Bohm

Quantum spin liquids (QSLs) are exotic phases of matter that host fractionalized excitations. It is difficult for local probes to characterize QSL, whereas quantum entanglement can serve as a powerful diagnostic tool due to its nonlocality. The kagome antiferromagnetic Heisenberg model is one of the most studied and experimentally relevant models for QSL, but its solution remains under debate. Here, we perform a numerical Aharonov-Bohm experiment on this model and uncover universal features of the entanglement entropy. By means of the density matrix renormalization group, we reveal the entanglement signatures of emergent Dirac spinons, which are the fractionalized excitations of the QSL. This scheme provides qualitative insights into the nature of kagome QSL and can be used to study other quantum states of matter. As a concrete example, we also benchmark our methods on an interacting quantum critical point between a Dirac semimetal and a charge-ordered phase.

Selective Quantum Annealing Using Transverse XY-Type Interaction

2012 ◽  
Vol 452-453 ◽  
pp. 1460-1464 ◽  
Author(s):  
Yohei Saika ◽  
Tetsuya Kakimoto ◽  
Jun Ichi Inoue
Keyword(s):  
Ground State ◽  
Statistical Physics ◽  
Wave Theory ◽  
Kinetic Term ◽  
Target System ◽  
Quantum Annealing ◽  
Initial State ◽  
Type Interaction ◽  
Quantum Spins ◽  
Ferromagnetic Interactions

We investigated quantum annealing (QA) via the transverse interaction with XY-type anisotropy for a ground state problem for a small composed of 4 S=1/2 quantum spins interacting with anti-ferromagnetic interactions with each other. By solving the Schrodinger equation for the QA system, we found that a preferable solution can be derived by tuning the XY-type anisotropy of the kinetic term among multiple candidates of the QA system. Similar behavior was suggested from the static property obtained by the spin wave theory established in statistical physics. In addition, we clarified that the ground state of the target system can be obtained by the QA starting from an initial state including excited states of the kinetic term, if the interval of time of the QA is set to be large to some extent.

scholarly journals Quantum spin-liquid states in an organic magnetic layer and molecular rotor hybrid

2020 ◽  
Vol 117 (47) ◽  
pp. 29555-29560
Author(s):  
Péter Szirmai ◽  
Cécile Mézière ◽  
Guillaume Bastien ◽  
Pawel Wzietek ◽  
Patrick Batail ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Magnetic Layer ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Organic Crystals ◽  
Spin Liquids ◽  
Molecular Rotor ◽  
Low Dimensionality ◽  
Liquid States ◽  
Quantum Spin Liquid

The exotic properties of quantum spin liquids (QSLs) have continually been of interest since Anderson’s 1973 ground-breaking idea. Geometrical frustration, quantum fluctuations, and low dimensionality are the most often evoked material’s characteristics that favor the long-range fluctuating spin state without freezing into an ordered magnet or a spin glass at low temperatures. Among the few known QSL candidates, organic crystals have the advantage of having rich chemistry capable of finely tuning their microscopic parameters. Here, we demonstrate the emergence of a QSL state in [EDT-TTF-CONH2]2+[BABCO−] (EDT-BCO), where the EDT molecules with spin-1/2 on a triangular lattice form layers which are separated by a sublattice of BCO molecular rotors. By several magnetic measurements, we show that the subtle random potential of frozen BCO Brownian rotors suppresses magnetic order down to the lowest temperatures. Our study identifies the relevance of disorder in the stabilization of QSLs.

scholarly journals Giant isotropic magneto-thermal conductivity of metallic spin liquid candidate Pr2Ir2O7 with quantum criticality

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J. M. Ni ◽  
Y. Y. Huang ◽  
E. J. Cheng ◽  
Y. J. Yu ◽  
B. L. Pan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Critical Point ◽  
Quantum Critical Point ◽  
Magnetic Monopoles ◽  
Quantum Criticality ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Zero Field ◽  
Spin Liquids ◽  
Quantum Critical

AbstractSpin liquids are exotic states with no spontaneous symmetry breaking down to zero-temperature because of the highly entangled and fluctuating spins in frustrated systems. Exotic excitations like magnetic monopoles, visons, and photons may emerge from quantum spin ice states, a special kind of spin liquids in pyrochlore lattices. These materials usually are insulators, with an exception of the pyrochlore iridate Pr2Ir2O7, which was proposed as a metallic spin liquid located at a zero-field quantum critical point. Here we report the ultralow-temperature thermal conductivity measurements on Pr2Ir2O7. The Wiedemann–Franz law is verified at high fields and inferred at zero field, suggesting no breakdown of Landau quasiparticles at the quantum critical point, and the absence of mobile fermionic excitations. This result puts strong constraints on the description of the quantum criticality in Pr2Ir2O7. Unexpectedly, although the specific heats are anisotropic with respect to magnetic field directions, the thermal conductivities display the giant but isotropic response. This indicates that quadrupolar interactions and quantum fluctuations are important, which will help determine the true ground state of this material.

scholarly journals Emergent spin-liquid-like state in the bond-disordered breathing pyrochlore

2020 ◽  
Author(s):  
Suheon Lee ◽  
Seunghwan Do ◽  
W.-J. Lee ◽  
Y.-S. Choi ◽  
Johan Van Tol ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Quantum Spin ◽  
Spin Fluctuations ◽  
Spin Liquid ◽  
Spin Liquids ◽  
Magnetic Ground State ◽  
Magnetic Specific Heat ◽  
State Of Matter

Abstract A breathing pyrochlore system is predicted to host a variety of quantum spin liquids. However, perturbations beyond nearest-neighbor Heisenberg interaction are an obstacle to identifying such exotic states. Here, we utilize a bond-alternating disorder to tune a magnetic ground state in the Cr-based breathing pyrochlore. By combining thermodynamic and magnetic resonance techniques, we provide experimental signatures of a spin-liquid-like state in LiGa1-xInxCr4O8 (x=0.2), namely, a nearly T2-dependent magnetic specific heat and a persistent spin dynamics by muon spin relaxation (μSR). Moreover, 7Li NMR, ZF-μSR, and ESR unveil the dichotomic nature of both temporal and thermal spin fluctuations: slowly fluctuating tetramer singlets at high temperatures and a fast fluctuating spin-liquid-like state at low temperatures. Our results suggest that a bond disorder in the breathing pyrochlore offers a new route to achieve an unexplored state of matter.

scholarly journals Quantum spin liquids

Science ◽  
2020 ◽  
Vol 367 (6475) ◽  
pp. eaay0668 ◽  
Author(s):  
C. Broholm ◽  
R. J. Cava ◽  
S. A. Kivelson ◽  
D. G. Nocera ◽  
M. R. Norman ◽  
...  
Keyword(s):  
Ground State ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Spin Liquids ◽  
Quantum Phases ◽  
Quantum Spin Liquids ◽  
The Past ◽  
Quantum Spin Liquid ◽  
Single Material ◽  
Topological Character

Spin liquids are quantum phases of matter with a variety of unusual features arising from their topological character, including “fractionalization”—elementary excitations that behave as fractions of an electron. Although there is not yet universally accepted experimental evidence that establishes that any single material has a spin liquid ground state, in the past few years a number of materials have been shown to exhibit distinctive properties that are expected of a quantum spin liquid. Here, we review theoretical and experimental progress in this area.

scholarly journals New insights into the structural properties of κ-(BEDT-TTF)2Ag2(CN)3 spin liquid

2020 ◽  
Vol 76 (4) ◽  
pp. 581-590 ◽  
Author(s):  
Pascale Foury-Leylekian ◽  
Vita Ilakovac ◽  
Pierre Fertey ◽  
Victor Baledent ◽  
Ognjen Milat ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Transition Metal ◽  
Symmetry Breaking ◽  
Physical Properties ◽  
Room Temperature ◽  
Spin Liquid ◽  
Monoclinic Structure ◽  
Spin Liquids ◽  
Anionic Layer ◽  
The Difference

Here, the first accurate study is presented of the room-temperature and 100 K structures of one of the first organic spin liquids, κ-(BEDT-TTF)2Ag2(CN)3. It is shown that the monoclinic structure determined previously is only the average one. It is shown that the exact structure presents triclinic symmetry with two non-equivalent dimers in the unit cell. But surprisingly this does not lead to a sizeable charge disproportionation between dimers. The difference from the analogue compound κ-(BEDT-TTF)2Cu2(CN)3 which also presents a spin liquid phase is discussed in detail. The data provided here show the importance of the anionic layer and in particular the transition metal position in the process of symmetry breaking. The possible impact of the symmetry breaking, albeit weak, on the spin-liquid mechanism and the influence of various disorders on the physical properties of this system is also discussed.

scholarly journals A Field Guide to Spin Liquids

2019 ◽  
Vol 10 (1) ◽  
pp. 451-472 ◽  
Author(s):  
J. Knolle ◽  
R. Moessner
Keyword(s):  
Theoretical Models ◽  
Gauge Fields ◽  
Spin Liquid ◽  
Majorana Fermions ◽  
Topological Phases ◽  
Spin Liquids ◽  
Promising Candidate ◽  
Short Supply ◽  
Quantum Matter ◽  
Characteristic Features

Spin liquids are collective phases of quantum matter that have eluded discovery in correlated magnetic materials for over half a century. Theoretical models of these enigmatic topological phases are no longer in short supply. In experiment there also exist plenty of promising candidate materials for their realization. One of the central challenges for the clear diagnosis of a spin liquid has been to connect the two. From that perspective, this review discusses characteristic features in experiment, resulting from the unusual properties of spin liquids. This takes us to thermodynamic, spectroscopic, transport, and other experiments on a search for traces of emergent gauge fields, spinons, Majorana fermions, and other fractionalized particles.

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