scholarly journals Pressure-Tuned Superconducting Dome in Chemically-Substituted κ-(BEDT-TTF)2Cu2(CN)3

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 817
Author(s):  
Yohei Saito ◽  
Anja Löhle ◽  
Atsushi Kawamoto ◽  
Andrej Pustogow ◽  
Martin Dressel
Keyword(s):  
Superconducting State ◽  
Low Temperatures ◽  
Magnetic Order ◽  
Ambient Pressure ◽  
Mott Insulator ◽  
Quantum Spin ◽  
Spin Liquid ◽  
First Order ◽  
Insulator Metal Transition ◽  
Quantum Spin Liquid

The quantum spin liquid candidate κ-(BEDT-TTF)2Cu2(CN)3 has been established as the prime example of a genuine Mott insulator that can be tuned across the first-order insulator–metal transition either by chemical substitution or by physical pressure. Here, we explore the superconducting state that occurs at low temperatures, when both methods are combined, i.e., when κ-[(BEDT-TTF)1−x(BEDT-STF)x]2Cu2(CN)3 is pressurized. We discovered superconductivity for partial BEDT-STF substitution with x = 0.10–0.12 even at ambient pressure, i.e., a superconducting state is realized in the range between a metal and a Mott insulator without magnetic order. Furthermore, we observed the formation of a superconducting dome by pressurizing the substituted crystals; we assigned this novel behavior to disorder emanating from chemical tuning.

Quantum spin liquid: design of a quantum spin liquid next to a superconducting state based on a dimer-type ET Mott insulator

2015 ◽  
Vol 3 (6) ◽  
pp. 1378-1388 ◽  
Author(s):  
Takaaki Hiramatsu ◽  
Yukihiro Yoshida ◽  
Gunzi Saito ◽  
Akihiro Otsuka ◽  
Hideki Yamochi ◽  
...  
Keyword(s):  
Superconducting State ◽  
Material Design ◽  
Mott Insulator ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Quantum Spin Liquid

We propose the material design for a quantum spin liquid next to a superconducting state based on a dimer-type ET Mott insulator.

scholarly journals From magnetic order to quantum disorder in the Zn-barlowite series of S = 1/2 kagomé antiferromagnets

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Katherine Tustain ◽  
Brendan Ward-O’Brien ◽  
Fabrice Bert ◽  
Tianheng Han ◽  
Hubertus Luetkens ◽  
...  
Keyword(s):  
Long Range ◽  
Ground State ◽  
Density Functional ◽  
Magnetic Order ◽  
Parent Compound ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Range Magnetic Order ◽  
Quantum Spin Liquid ◽  
Long Range Magnetic Order

Abstract We report a comprehensive muon spectroscopy study of the Zn-barlowite series of $$S=\frac{1}{2}$$ S = 1 2 kagomé antiferromagnets, ZnxCu4−x(OH)6FBr, for x = 0.00 to 0.99(1). By combining muon spin relaxation and rotation measurements with state-of-the-art density-functional theory muon-site calculations, we observe the formation of both μ–F and μ–OH complexes in Zn-barlowite. From these stopping sites, implanted muon spins reveal the suppression of long-range magnetic order into a possible quantum spin liquid state upon the increasing concentration of Zn-substitution. In the parent compound (x = 0), static long-range magnetic order below TN = 15 K manifests itself in the form of spontaneous oscillations in the time-dependent muon asymmetry signal consistent with the dipolar fields expected from the calculated muon stopping sites and the previously determined magnetic structure of barlowite. Meanwhile, in the x = 1.0 end-member of the series—in which antiferromagnetic kagomé layers of Cu2+$$S=\frac{1}{2}$$ S = 1 2 moments are decoupled by diamagnetic Zn2+ ions—we observe that dynamic magnetic moment fluctuations persist down to at least 50 mK, indicative of a quantum disordered ground state. We demonstrate that this crossover from a static to dynamic magnetic ground state occurs for compositions of Zn-barlowite with x > 0.5, which bears resemblance to the dynamical behaviour of the widely studied Zn-paratacamite series that contains the quantum spin liquid candidate herbertsmithite.

scholarly journals Chemical tuning of the molecular quantum materials κ-[(BEDT-TTF)1-x(BEDT-STF)x]2Cu2(CN)3: from Mott-insulating quantum spin liquid to metallic Fermi liquid

2021 ◽  
Author(s):  
Yohei Saito ◽  
Roland Rösslhuber ◽  
Anja Löhle ◽  
Miriam Sanz Alonso ◽  
Maxim Wenzel ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electronic Properties ◽  
Fermi Liquid ◽  
Mott Insulator ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Molecular Conductors ◽  
Chemical Pressure ◽  
Metal Phase Transition ◽  
Quantum Spin Liquid

The electronic properties of molecular conductors can be readily varied via physical or chemical pressure as it increases the bandwidth W; this enables crossing the Mott insulator-to-metal phase transition by...

scholarly journals Gapless quantum spin liquid in a honeycomb Γ magnet

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Qiang Luo ◽  
Jize Zhao ◽  
Hae-Young Kee ◽  
Xiaoqun Wang
Keyword(s):  
Ground State ◽  
Magnetic Order ◽  
Energy Gap ◽  
Entanglement Entropy ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Spin Liquids ◽  
Complete Understanding ◽  
Quantum Spin Liquids ◽  
Quantum Spin Liquid

AbstractA family of spin–orbit coupled honeycomb Mott insulators offers a playground to search for quantum spin liquids (QSLs) via bond-dependent interactions. In candidate materials, a symmetric off-diagonal Γ term, close cousin of Kitaev interaction, has emerged as another source of frustration that is essential for complete understanding of these systems. However, the ground state of honeycomb Γ model remains elusive, with a suggested zigzag magnetic order. Here we attempt to resolve the puzzle by perturbing the Γ region with a staggered Heisenberg interaction which favours the zigzag ordering. Despite such favour, we find a wide disordered region inclusive of the Γ limit in the phase diagram. Further, this phase exhibits a vanishing energy gap, a collapse of excitation spectrum, and a logarithmic entanglement entropy scaling on long cylinders, indicating a gapless QSL. Other quantities such as plaquette-plaquette correlation are also discussed.

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 Gapless Quantum Spin Liquid in the Triangular System Sr3CuSb2O9

2020 ◽  
Vol 125 (26) ◽  
Author(s):  
S. Kundu ◽  
Aga Shahee ◽  
Atasi Chakraborty ◽  
K. M. Ranjith ◽  
B. Koo ◽  
...  
Keyword(s):  
Quantum Spin ◽  
Spin Liquid ◽  
Triangular System ◽  
Quantum Spin Liquid

scholarly journals Giant phonon anomalies in the proximate Kitaev quantum spin liquid α-RuCl3

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Haoxiang Li ◽  
T. T. Zhang ◽  
A. Said ◽  
G. Fabbris ◽  
D. G. Mazzone ◽  
...  
Keyword(s):  
Acoustic Phonon ◽  
Energy Scale ◽  
Quantum Spin ◽  
Majorana Fermion ◽  
Spin Liquid ◽  
Optical Phonons ◽  
Large Intensity ◽  
Topological Quantum ◽  
Topological State ◽  
Quantum Spin Liquid

AbstractThe Kitaev quantum spin liquid epitomizes an entangled topological state, for which two flavors of fractionalized low-energy excitations are predicted: the itinerant Majorana fermion and the Z2 gauge flux. It was proposed recently that fingerprints of fractional excitations are encoded in the phonon spectra of Kitaev quantum spin liquids through a novel fractional-excitation-phonon coupling. Here, we detect anomalous phonon effects in α-RuCl3 using inelastic X-ray scattering with meV resolution. At high temperature, we discover interlaced optical phonons intercepting a transverse acoustic phonon between 3 and 7 meV. Upon decreasing temperature, the optical phonons display a large intensity enhancement near the Kitaev energy, JK~8 meV, that coincides with a giant acoustic phonon softening near the Z2 gauge flux energy scale. These phonon anomalies signify the coupling of phonon and Kitaev magnetic excitations in α-RuCl3 and demonstrates a proof-of-principle method to detect anomalous excitations in topological quantum materials.

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