Recent work has highlighted remarkable effects of classical thermal fluctuations in the dipolar spin ice compounds, such as "artificial magnetostatics", manifesting Coulombic power-law correlations and particles behaving diffusive "magnetic monopoles". In this paper, we address quantum ice, giving a unifying framework for study magnetism large class magnetic compounds with pyrochlore structure, particular discuss Yb2Ti2O7 extract its full set Hamiltonian parameters from high field inelastic...

We develop a non-perturbative "gauge Mean Field Theory" (gMFT) method to study general effective spin-1/2 model for magnetism in rare earth pyrochlores. gMFT is based on novel exact slave-particle formulation, and matches both the perturbative regime near classical spin ice limit semiclassical approximation far from it. show that full phase diagram contains two exotic phases: quantum liquid coulombic ferromagnet, of which support deconfined spinon excitations emergent electrodynamics....

Here we establish the systematic existence of a U(1) degeneracy all symmetry-allowed Hamiltonians quadratic in spins on pyrochlore lattice, at mean-field level. By extracting Hamiltonian Er(2)Ti(2)O(7) from inelastic neutron scattering measurements, then show that U(1)-degenerate states are its classical ground states, and unambiguously quantum fluctuations break way which is confirmed by experiment. The degree symmetry protection unprecedented other materials. As consequence, our...

We propose that in a certain class of magnetic materials, known as non-Kramers ``spin ice,'' disorder induces quantum entanglement. Instead driving glassy behavior, provokes superpositions spins throughout the system and engenders an associated emergent gauge structure set fractional excitations. More precisely, transforms classical phase governed by large entropy, spin ice, into liquid As degree is increased, transitions between (i) ``regular'' Coulombic liquid, (ii) ``Mott glass,'' which...

We consider the effect of coupling between phonons and a chiral Majorana edge in gapped spin liquid with Ising anyons (e.g., Kitaev's non-Abelian on honeycomb lattice). This is especially important regime which longitudinal bulk heat conductivity $\kappa_{xx}$ due to much larger than expected quantized thermal Hall conductance $\kappa_{xy}^{\rm q}=\frac{\pi T}{12} \frac{k_B^2}{\hbar}$ ideal isolated mode, so that angle, i.e., angle current temperature gradient, small. By modeling interaction...

Magnetic fluctuations and electrons couple in intriguing ways the vicinity of zero temperature phase transitions - quantum critical points conducting materials. Quantum criticality is implicated non-Fermi liquid behavior diverse materials, formation unconventional superconductors. Here we uncover an entirely new type point describing onset antiferromagnetism a nodal semimetal engendered by combination strong spin-orbit coupling electron correlations, which predicted to occur iridium oxide...

The discovery of superconductivity in the $j$=$\frac{3}{2}$ spin-orbit coupled half-Heusler semimetals has given field low-density a new twist. Exotic pairings are likely, yet favored superconducting instabilities remain to be determined. authors provide method analyze systems with symmetry-protected band touchings. They apply it find that polar phonons play an important role mechanism compounds. also explicitly show number features associated such structures, as strong dependence on hole or...

Mind the angle Interplay between real- and momentum-space properties of materials can lead to exotic phenomena. Suzuki et al. studied electrical transport in presence a magnetic field cerium-aluminum-germanium, Weyl semimetal that also harbors magnetism (see Perspective by Hassinger Meng). As they varied orientation applied field, noticed spikes resistivity sharply centered around high symmetry axes material. The were consequence small overlap Fermi surfaces—which “live” momentum space—on...

Quantum spin liquids are highly entangled ground states of quantum systems with an emergent gauge structure, fractionalized spinon excitations, and other unusual properties. While these features clearly distinguish from conventional, mean-field-like at zero temperature ($T$), their status $T>0$ is less clear. Strictly speaking, it known that most lose identity nonzero temperature, being then adiabatically transformable into a trivial paramagnet. This the case for $U(1)$ liquid recently...

We study the topological properties of superconductors with paired $j=\frac{3}{2}$ quasiparticles. Higher spin Fermi surfaces can arise, for instance, in strongly spin-orbit coupled band-inverted semimetals. Examples include Bi-based half-Heusler materials, which have recently been established as low-temperature and low-carrier density superconductors. Motivated by this experimental observation, we obtain a comprehensive symmetry-based classification pairing states systems higher angular...

The Coulombic quantum spin liquid in ice is an exotic phase of matter that emerges on the pyrochlore lattice and currently actively searched for. Motivated by recent experiments Yb-based breathing material ${\mathrm{Ba}}_{3}{\mathrm{Yb}}_{2}{\mathrm{Zn}}_{5}{\mathrm{O}}_{11}$, we theoretically study diagram magnetic properties relevant model. latter takes form a Hamiltonian lattice, analyze stability absence inversion symmetry which breaks explicitly at sites. Using gauge mean-field...

Because electrons and ions form a coupled system, it is priori clear that the dynamics of lattice should reflect symmetry breaking within electronic degrees freedom. Recently, this has been clearly evidenced for case time-reversal mirror by observations large phononic thermal Hall effect in many strongly correlated materials. However, mechanism which chirality communicated to far from evident. In paper, we discuss how occurs via many-body scattering phonons collective modes: consequence...

We consider the effects of local impurities in highly frustrated diamond lattice antiferromagnets, which exhibit large but non-extensive ground state degeneracies. Such models are appropriate to many A-site magnetic spinels. argue very generally that sufficiently dilute induce an ordered state, and provide a mechanism degeneracy breaking. The states selected can be determined by "swiss cheese model" analysis, we demonstrate numerically for particular impurity model this case. Moreover,...

We investigate twisted bilayer graphene near charge neutrality using a generalized Bistritzer-MacDonald continuum model accounting for corrugation effects. The Fermi velocity vanishes particular twist angles properly reproducing the physics of celebrated magic angles. Using group representation theory, we identify all contact interaction potentials compatible with symmetries model. This enables us to two classes quartic interactions leading either opening gap or nematic ordering. then...

We propose a general scheme for the derivation of signals resonant inelastic (and elastic) x-ray scattering (RIXS) gives access to. In particular, we find that RIXS should allow to directly detect many hidden orders, such as spin nematic, bond vector and scalar chiralities. To do so, choose take point view effective operators, leaving microscopic details unspecified, but still keeping experimentally-controllable parameters explicit, like incoming outgoing polarizations x-rays. ask not what...

We study the intrinsic scattering of phonons by a general quantum degree freedom, i.e. fluctuating "field" $Q$, which may have completely correlations, restricted only unitarity and translational invariance. From induced rates, we obtain consequences on thermal conductivity tensor phonons. find that lowest-order diagonal rate, determines longitudinal conductivity, is controlled two-point correlation functions $Q$ field, while off-diagonal rates involve minimum three to four point functions....

We study the intrinsic scattering of phonons by a general quantum degree freedom, i.e. fluctuating "field" $Q$, which may have completely correlations, restricted only unitarity and translational invariance. From induced rates, we obtain consequences on thermal conductivity tensor phonons. find that lowest-order diagonal rate, determines longitudinal conductivity, is controlled two-point correlation functions $Q$ field, while off-diagonal rates involve minimum three to four point functions....

Domains in noncentrosymmetric materials represent regions of different crystal structure and spin-orbit coupling. Twin boundaries separating such domains display unusual properties superconductors (NCSs), where magnetoelectric effects influence the local lower upper critical magnetic fields. As a model system, we investigate NCSs with tetragonal Rashba coupling (RSOC), twin parallel to their basal planes. There, report that there are two types which separate opposite RSOC. In field plane,...

The search for truly quantum phases of matter is a center piece modern research in condensed physics. Quantum spin liquids, which host large amounts entanglement-an entirely feature where one part system cannot be measured without modifying the rest-are exemplars such phases. Here, we devise realistic model relies upon well-known Haldane chain phase, i.e. phase spin-1 chains fractional excitations at their ends, akin to hallmark liquids. We tune our exactly soluble points, and find that...

We systematically derive the quantum kinetic equation in full phase space for any quadratic Hamiltonian of bosonic fields, including absence translational invariance. This enables treatment boundaries, inhomogeneous systems, and states with nontrivial textures, such as skyrmions context magnetic bosons. relate evolution distribution bosons to single-electron, band-diagonal physical quantities Berry curvature energy magnetization by providing a procedure ``diagonalize'' space, using formalism...

The $S=1$ bilinear-biquadratic Heisenberg exchange model on the triangular lattice with a single-ion anisotropy has previously been shown to host number of exotic magnetic and nematic orders [Moreno-Cardoner et al., Phys. Rev. B 90, 144409 (2014)], including an extensive region ``supersolid'' order. In this work, we amend by $XXZ$ in interactions. Tuning limit exactly solvable generalized Ising-/Blume-Capel-type provides controlled access phases at finite transverse exchange. Notably, find...