arXiv subjects

Inti Sodemann Villadiego

Publications and source records attributed to Inti Sodemann Villadiego.

At least 19 recordsLinked to original sources

arXiv2026

Anyon polarons as a window into the competing phases of the Kitaev-Gamma-Gamma-prime model

We investigate the dispersions of anyon quasiparticles in the Kitaev honeycomb spin liquid perturbed by $Γ$ and $Γ'$ couplings in order to understand phase transitions into competing states through anyon gap-closing instabilities. We demonstrate how anyon gap closings provide a way to understand phase transitions into a plethora of previously identified competing phases---including zigzag, stripy, $120^\circ$, and incommensurate spiral phases---and are in agreement with numerical studies not only on the nature of the phases, but also on the specific critical values of $Γ$ and $Γ'$ couplings. Remarkably, when the antiferromagnetic Kitaev model is perturbed by a negative $Γ$ interaction, we find that the single-vison and fermion gaps remain open while the gap of a magnon-like local boson vanishes. This points to a plausible candidate coexistence regime where long-range magnetic order emerges while fractionalized excitations inherited from the Kitaev spin liquid may persist. The magnetic order can be either stripy antiferromagnetic or incommensurate spiral, depending on the sign of $Γ'$.

cond-mat.str-el↗

arXiv2026

High-Temperature Quantum Oscillations of a Non-equilibrium Non-Fermi Liquid

A periodically driven Fermi gas coupled to a simple boson bath reaches a non-equilibrium steady-state occupation with sharp non-analyticities at certain momenta. Here, we demonstrate that these non-analyticities behave as emergent Fermi surfaces by showing that they give rise to quantum oscillations of observables with a period controlled by the effective Fermi surface area enclosed by these non-analyticities. However, these oscillations have several striking differences with standard equilibrium quantum oscillations. For example, they remain non-analytic at finite temperatures, their amplitude can survive up to extremely high temperatures comparable to the frequency of the drive, and they can display non-monotonic temperature dependence completely at odds with standard Lifshits-Kosevich behavior.

cond-mat.mes-hall↗

arXiv2026

The monopole plasma resonance: a smoking gun of 3D $U(1)$ quantum spin liquids

Certain 3D $U(1)$ spin liquids, such as those arising in dipolar quantum spin ice, have an emergent monopole which is the source of an emergent magnetic field that transforms under symmetries like an electric polarization. As a consequence, these monopoles carry a physical electric charge in their cores and form a plasma at low temperatures. Due to the monopole coupling to emergent gauge fields, the full system behaves as an electrical insulator for DC transport, but can display a sharp plasma resonance analogous to a metal at very low frequencies. This can serve as a clear fingerprint to detect these states in materials. We discuss the optimal conditions to observe this phenomenon in the 3D $U(1)$ spin-liquid candidate Ce$_2$Zr$_2$O$_7$.

cond-mat.str-el↗

arXiv2025

Localized Excitons and Landau-Level Mixing in Time-Reversal Symmetric Pairs of Chern Bands

We study Landau-level mixing in a time-reversal-symmetric Hamiltonian composed of two sets of Landau levels with opposite magnetic field, relevant to moiré minibands in twisted homobilayer transition-metal dichalcogenides in the adiabatic limit, where electrons in opposite valleys have flat Chern bands with opposite Chern numbers. Strong spin-orbit coupling polarizes spins in opposite directions in opposite valleys, separating Coulomb interactions into like-spin ($V^{\uparrow\uparrow}$) and opposite-spin ($V^{\uparrow\downarrow}$). Using degenerate perturbation theory, we compute Landau-level mixing corrections to $V^{\uparrow\uparrow}$ and $V^{\uparrow\downarrow}$ for different filling fractions. In the lowest Landau level, screening exhibits an even-odd effect: $V^{\uparrow\uparrow}$ is reduced more strongly than $V^{\uparrow\downarrow}$ in even-$m$ angular momentum Haldane pseudopotential and less strongly in odd-$m$ angular momentum ones. In the first Landau level, the short-range part ($m=0,1$) of $V^{\uparrow\downarrow}$ is reduced comparably to $V^{\uparrow\uparrow}$, while the strongest spin anisotropy appears in the $m=2$ pseudopotential. These novel short-range spin correlations have important implications for candidate correlated phases of fractional quantum spin Hall insulators. A distinctive feature of this time-reversal-symmetric Hamiltonian, absent in conventional quantum Hall systems, is that spin-flip excitations form localized quasiparticles. We compute their excitation spectrum and predict a non-monotonic dependence of the ordering temperature of Chern ferromagnetism in MoTe$_2$ on the Landau-level mixing parameter.

cond-mat.str-el↗

arXiv2025

Instability of Laughlin FQH liquids into gapless power-law correlated states with continuous exponents in ideal Chern bands: rigorous results from plasma mapping

We investigate the fate of Laughlin's wave-function in ideal Chern bands which can be mapped to generalized zero Landau levels in spatially dependent magnetic fields. By exploiting its exact mapping onto a classical Coulomb gas and leveraging previous results of one-component plasmas in nonuniform neutralizing backgrounds, we demonstrate that the ideal Laughlin wave-function undergoes a phase transition from its well-known fully gapped topologically ordered plasma state into a power-law correlated dielectric state even for the fixed filling of $1/3$, as the magnetic field becomes increasingly more inhomogeneous. This dielectric state is gapless even though it does not spontaneously break translational symmetry. Remarkably, for a fixed filling $ν=1/m$, the exponent governing density correlations in this state changes continuously as a function of the degree of spatial inhomogeneity of the magnetic field, and can range from $4$ near a Berezinskii-Kosterlitz-Thouless transition to the plasma state, up to $2 m$ in the limit of fields generated by point solenoids.

cond-mat.str-el↗

arXiv2025

Anyon polarons as a window into competing phases of the Kitaev honeycomb model under a Zeeman field

We compute the spectra of anyon quasiparticles in all three super-selection sectors of the Kitaev model (i.e., visons, fermions and bosons), perturbed by a Zeeman field away from its exactly solvable limit, to gain insights on the competition of its non-abelian spin-liquid with other nearby phases, such as the mysterious intermediate state observed in the antiferromagnetic model. Both for the ferro- and antiferro-magnetic models we find that the fermions and visons become gapless at nearly identical critical Zeeman couplings. In the ferromagnetic model this is consistent with a direct transition into a polarized state. In the anti-ferromagnetic model this implies that previous theories of the intermediate phase viewed as a spin liquid with a different fermion Chern number are inadequate, as they presume that the vison gap does not close. In the antiferromagnetic model we also find that a bosonic quasiparticle becomes gapless at nearly the same critical field as the fermions and visons. This boson carries the quantum numbers of an anti-ferromagnetic order parameter, suggesting that the intermediate phase has spontaneously broken symmetry with this order.

cond-mat.str-el↗

arXiv2025

Ultra-critical Floquet Non-Fermi Liquid

We demonstrate that periodically driven Fermions coupled to simple bosonic baths have steady state occupations of Floquet Bloch bands that generically display non-analyticties at certain momenta which resemble the Fermi surfaces of equilibrium non-Fermi liquids. Remarkably these non-equilibrium Fermi surfaces remain sharp even when the bath is at finite temperature, leading to critical power-law decaying correlations at finite temperature, a phenomenon with no analogue in equilibrium. We also show that generically there is in-gap current rectification for clean metals lacking inversion symmetry, and explain why this occurs universally regardless of the details of collisions.

cond-mat.mes-hall↗

arXiv2024

Non-linear Faraday Precession of Light Polarization in Time-Reversal Invariant Materials

We investigate the propagation of electromagnetic waves through materials displaying a non-linear Hall effect. The coupled Maxwell-Boltzmann equations for traveling waves can be mapped onto ordinary differential equations that resemble those for the motion of a pendulum. In the weakly non-linear regime relevant for most experiments, we find that the polarization of light displays a Faraday-like precession of its polarization direction that swings back and forth around the direction of Berry dipole vector as the light beam traverses the material. This occurs concomitantly with an oscillation of its degree of polarization, with a characteristic frequency that increases linearly with the intensity of the traveling wave. These effects could be observed by measuring thickness dependent Faraday rotations as well as the emission of lower frequency radiation associated with the polarization oscillations in materials displaying the non-linear Hall effect.

cond-mat.mes-hall↗

arXiv2024

Berry phase effects on the transverse conductivity of Fermi surfaces and their detection via spin qubit noise magnetometry

The quasi-static transverse conductivity of clean Fermi liquids at long wavelengths displays a remarkably universal behaviour: it is determined solely by the radius of curvature of the Fermi surface and does not depend on details such as the quasi-particle mass or their interactions. Here we demonstrate that Berry phases do not alter such universality by directly computing the transverse conductivity of two-dimensional electronic systems with Dirac dispersions, such as those appearing in graphene and its chiral multilayer variants. Interestingly, however, such universality ceases to hold at wave-vectors comparable to the Fermi radius, where Dirac fermions display a vividly distict transverse conductivity relative to parabolic Fermions, with a rich wave-vector dependence that includes divergences, oscillations and zeroes. We discuss how this can be probed by measuring the $T_1$ relaxation time of spin qubits, such as NV centers or nuclear spins, placed near such 2D systems.

cond-mat.mes-hall↗

arXiv2024

Realization of topological Thouless pumping in a synthetic Rydberg dimension

The simulation of synthetic dimensions by manipulating internal states of atoms and molecules has opened the door to investigate regimes outside those of more traditional quantum many-body platforms. Highly excited Rydberg states of atoms are a particularly promising platform to engineer Hamiltonians in such synthetic dimensions due to their large number of addressable states and the readily available technologies for manipulating their couplings and for detecting them. In this letter, we demonstrate the realization of topological quantum pumping in synthetic dimensions by engineering a one-dimensional Rice-Mele chain from the Rydberg states of cesium atoms, and manipulating their couplings in a time-dependent fashion through radio-frequency fields. We implement Thouless protocols for topological pumping and investigate the efficiency for pumping an effective quantum particle as a function of the period of pumping and other parameters while allowing for rates of change that are not necessarily adiabatic. We demonstrate that optimal pumping efficiencies of up to 90% can be achieved when the pump is operated in the topological Thouless regime, even when the pumping is accompanied by the wave-packet spread that arises from the energy dispersion of the particle along the synthetic dimension.

quant-ph↗

arXiv2024

Halperin States of Particles and Holes in Ideal Time Reversal Invariant Pairs of Chern Bands and The Fractional Quantum Spin Hall Effect in Moiré MoTe$_2$

An experiment in moiré MoTe$_2$ bilayers reported the first observation of a topologically ordered state with zero Hall conductivity and half of the edge conductance of a standard time-reversal invariant quantum spin Hall insulator. This state is believed to emerge at total filling one of a pair of bands with Chern numbers $C=\pm1$ related by time reversal symmetry. By viewing these bands as a pair of Landau levels with opposite magnetic fields, and starting from a parent magnet with one filled band, we demonstrate that a class of Halperin states constructed by adding particles to the empty Chern band and holes to the occupied Chern band have all the properties observed in MoTe$_2$. Remarkably, these states break time-reversal symmetry but have exactly zero Hall conductivity and helical edge conductance of $e^2/2h$. These states also feature a spinless composite fermion with the same charge as the electron but split equally between both valleys. In a standard Halperin 331 state, this particle would be a neutral Bogoliubov composite fermion. However, in our context this composite fermion is charged but remains itinerant because it is split into the two valleys that effectively experience opposite magnetic fields. The existence of such charged itinerant particles is a key difference between Landau levels with opposite magnetic fields and standard multi-components Landau levels, where all the itinerant particles are charge neutral, such as the magneto-roton of the Laughlin state or the Bogoliubov composite fermion of the Moore-Read state. When the electron density changes away from the ideal filling and these itinerant charged particles are added to the parent state, the disorder potential is less efficient at localizing them as compared to standard Lanadau levels. This can explain why the state in MoTe$_2$ did not display a robust Hall plateau upon changing the electron density.

cond-mat.mes-hall↗

arXiv2024

Landau-Level Mixing and SU(4) Symmetry Breaking in Graphene

Recent scanning tunneling microscopy experiments on graphene at charge neutrality under strong magnetic fields have uncovered a ground state characterized by Kekulé distortion (KD). In contrast, non-local spin and charge transport experiments in double-encapsulated graphene, which has a higher dielectric constant, have identified an antiferromagnetic (AF) ground state. We propose a mechanism to reconcile these conflicting observations, by showing that Landau-level mixing can drive a transition from AF to KD with the reduction of the dielectric screening. Our conclusion is drawn from studying the effect of Landau-level mixing on the lattice-scale, valley-dependent interactions to leading order in graphene's fine structure constant $κ= e^2/(\hbar v_F ε)$. This analysis provides three key insights: 1) Valley-dependent interactions remain predominantly short-range with the $m=0$ Haldane pseudopotential being at least an order of magnitude greater than the others, affirming the validity of delta-function approximation for these interactions. 2) The phase transition between the AF and KD states is driven by the microscopic process in the double-exchange Feynman diagram. 3) The magnitudes of the coupling constants are significantly boosted by remote Landau levels. Our model also provides a theoretical basis for numerical studies of fractional quantum Hall states in graphene.

cond-mat.mes-hall↗

arXiv2023

Jordan-Wigner composite-fermion liquids in 2D quantum spin-ice

The Jordan-Wigner map in 2D is as an exact lattice regularization of the 2 pi-flux attachment to a hard-core boson (or spin-1/2) leading to a composite-fermion particle. When the spin-1/2 model obeys ice rules this map preserves locality, namely, local Rohkshar-Kivelson models of spins are mapped onto local models of Jordan-Wigner/composite-fermions. Using this composite-fermion dual representation of RK models, we construct spin-liquid states by projecting Slater determinants onto the subspaces of the ice rules. Interestingly, we find that these composite-fermions behave as ``dipolar" partons for which the projective implementations of symmetries are very different from standard ``point-like" partons. We construct interesting examples of composite-fermion liquid states that respect all microscopic symmetries of the RK model. In the six-vertex subspace, we constructed a time-reversal and particle-hole-invariant state featuring two massless Dirac nodes, which is a composite-fermion counterpart to the classic pi-flux state of Abrikosov-Schwinger fermions in the square lattice. This state is a good ground state candidate for a modified RK-like Hamiltonian of quantum spin-ice. In the dimer subspace, we construct a state fearturing a composite Fermi surface but with nesting instabilities towards ordered phases such as the columnar state. We have also analyzed the low energy emergent gauge structure. If one ignores confinement, the system would feature a U(1) x U(1) low energy gauge structure with two associated gapless photon modes, but with the composite fermion carrying gauge charge only for one photon and behaving as a gauge neutral dipole under the other. These states are examples of pseudo-scalar U(1) spin liquids where mirror and time-reversal symmetries act as particle-hole conjugations, and the emergent magnetic fields are even under such time-reversal or lattice mirror symmetries.

cond-mat.str-el↗

arXiv2023

Spin-valley entangled quantum Hall states in graphene

We investigate interaction-driven integer quantum Hall states realized in Landau levels of monolayer graphene when two out of its four nearly degenerate spin-valley flavors are filled. By employing a model that accounts for interactions beyond pure delta-functions as well as Zeeman and substrate-induced valley potentials, we demonstrate the existence of a delicate competition of several phases with spontaneous generation of spin-valley entanglement, akin to the spontaneous appearance of spin-orbit coupling driven by interactions. We encounter a particular phase that we term the entangled-Kekulé-antiferromagnet (E-KD-AF) which only becomes spin-valley entangled under the simultaneous presence of Zeeman and substrate potentials, because it gains energy by simultaneously canting in the spin and valley spaces, by combining features of a canted anti-ferromagnet and a canted Kekulé state. We quantify the degree of spin-valley entanglement of the many competing phases by computing their bipartite concurrence.

cond-mat.mes-hall↗

arXiv2023

The Floquet Fermi Liquid

We demonstrate the existence of a non-equilibrium "Floquet Fermi Liquid" state arising in partially filled Floquet Bloch bands weakly coupled to ideal fermionic baths, which possess a collection of "Floquet Fermi surfaces" enclosed inside each other, resembling matryoshka dolls. We elucidate several properties of these states, including their quantum oscillations under magnetic fields which feature slow beating patterns of their amplitude reflecting the different areas of the Floquet Fermi surfaces, consistent with those observed in microwave induced resistance oscillation experiments. We also investigate their specific heat and thermodynamic density of states and demonstrate how by controlling properties of the drive, such as its frequency, one can tune some of the Floquet Fermi surfaces towards non-equilibrium van-Hove singularities without changing the electron density.

cond-mat.mes-hall↗

arXiv2023

Nature of visons in the perturbed ferromagnetic and antiferromagnetic Kitaev honeycomb models

The Kitaev honeycomb model hosts a fascinating fractionalized state of matter featuring emergent Majorana fermions and a vison particle that carries the flux of an emergent gauge field. In the exactly solvable model these visons are static but certain perturbations can induce their motion. We show that the nature of the vison motion induced by a Zeeman field is sharply distinct in the ferromagnetic vs the antiferromagnetic Kitaev models. Namely, in the ferromagnetic model the vison has a trivial non-projective translational symmetry, whereas in the antiferromagnetic Kitaev model it has a projective translational symmetry with $π$-flux per unit cell. The vison band of the ferromagnetic case has zero Berry curvature, and no associated intrinsic contribution to the thermal Hall effect. In contrast, in the antiferromagnetic case there are two gapped vison bands with opposite Chern numbers and an associated intrinsic vison contribution to the thermal Hall effect. We discuss these findings in the light of the physics of the spin liquid candidate $α$-RuCl$_3$.

cond-mat.str-el↗

arXiv2023

The Fermi-Dirac staircase occupation of Floquet bands and current rectification inside the optical gap of metals: a rigorous perspective

We consider a model of a Bloch band subjected to an oscillating electric field and coupled to a featureless fermionic heat bath, which can be solved exactly. We demonstrate rigorously that in the limit of vanishing coupling to this bath (so that it acts as an ideal thermodynamic bath) the occupation of the Floquet band is not a simple Fermi-Dirac distribution function of the Floquet energy, but instead it becomes a ``staircase'' version of this distribution. We show that this distribution generically leads to a finite rectified electric current within the optical gap of a metal even in the limit of vanishing carrier relaxation rates, providing a rigorous demonstration that such rectification is generically possible and clarifying previous statements in the optoelectronics literature. We show that this current remains non-zero even up to the leading perturbative second order in the amplitude of electric fields, and that it approaches the standard perturbative expression of the Jerk current obtained from a simpler Boltzmann description within a relaxation time approximation when the frequencies are small compared to the bandwidth.

cond-mat.mes-hall↗

arXiv2022

Theory of broken symmetry quantum Hall states in the $N=1$ Landau level of Graphene

We study many-body ground states for the partial integer fillings of the $N=1$ Landau level in graphene, by constructing a model that accounts for the lattice scale corrections to the Coulomb interactions. Interestingly, in contrast to the $N=0$ Landau level, this model contains not only pure delta function interactions but also some of its derivatives. Due to this we find several important differences with respect to the $N=0$ Landau level. For example at quarter filling when only a single component is filled, there is a degeneracy lifting of the quantum hall ferromagnets and ground states with entangled spin and valley degrees of freedom can become favourable. Moreover at half-filling of the $N=1$ Landau level, we have found a new phase that is absent in the $N=0$ Landau level, that combines characteristics of the Kekulé state and an antiferromagnet. We also find that according to the parameters extracted in a recent experiment, at half-filling of the $N=1$ Landau level graphene is expected to be in a delicate competition between an AF and a CDW state, but we also discuss why the models for these recent experiments might be missing some important terms.

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