A5024583708- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Quantum many-body systems
- Topological Materials and Phenomena
- Theoretical and Computational Physics
- Algebraic structures and combinatorial models
- Perovskite Materials and Applications
- Personal Information Management and User Behavior
- Quantum Chromodynamics and Particle Interactions
- Geological and Geochemical Analysis
- earthquake and tectonic studies
- Crystal Structures and Properties
- Atomic and Subatomic Physics Research
- Nuclear materials and radiation effects
University of Cambridge
2022-2024
University of Toronto
2017-2023
Recently, Co-based honeycomb magnets have been proposed as promising candidate materials to host the Kitaev spin liquid state. One of front-runners is BaCo$_2$(AsO$_4$)$_2$ (BCAO), where it was suggested that exchange processes between Co$^{2+}$ ions via surrounding edge-sharing oxygen octahedra could give rise bond-dependent interactions. In this work, we present and analyze comprehensive inelastic neutron scattering studies BCAO with fields in plane. Combining constraints from magnon...
The appearance of half-quantized thermal Hall conductivity in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ the presence in-plane magnetic fields has been taken as a strong evidence for Kitaev spin liquid. Apart from quantization, observed sign structure is also consistent with predictions exact solution honeycomb model. Namely, changes when field direction reversed respect to heat current, which perpendicular one three nearest neighbor bonds on lattice. On other hand, almost...
Thermal transport in topologically-ordered phases of matter provides valuable insights as it can detect the charge-neutral quasiparticles that would not directly couple to electromagnetic probes. An important example is edge heat Majorana fermions a chiral spin liquid, which leads half-quantized thermal Hall conductivity. This signature precisely what has recently been measured $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ under external magnetic fields. The plateau-like...
Symmetry fractionalization is a ubiquitous feature of topologically ordered states that can be used to classify different symmetry-enriched topological phases and reveal some their unique experimental signatures. Despite its vast popularity, there currently no available framework study symmetry quantum spin ice (QSI)---a $\text{U}(1)$ liquid (QSL) on the pyrochlore lattice supporting emergent photons---within most widely theoretical describe it, gauge mean-field theory (GMFT). In this work,...
Motivated by recent experiments on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:msub><a:mi>Ce</a:mi><a:mn>2</a:mn></a:msub><a:msub><a:mi>Zr</a:mi><a:mn>2</a:mn></a:msub><a:msub><a:mi mathvariant="normal">O</a:mi><a:mn>7</a:mn></a:msub></a:mrow></a:math> that reveal a dynamic, liquidlike ground state, we study the nearest-neighbor XYZ Hamiltonian of dipolar-octupolar pyrochlore magnets with pseudofermion functional renormalization group (PFFRG), which is numerically...
The appearance of nontrivial phases in Kitaev materials exposed to an external magnetic field has recently been a subject intensive studies. Here, we elucidate the relation between field-induced ground states classical and quantum spin models proposed for such materials, by using infinite density matrix renormalization group (iDMRG) linear wave theory (LSWT). We consider $K \Gamma \Gamma'$ model, where $\Gamma$ $\Gamma'$ are off-diagonal exchanges on top dominant interaction $K$. Focusing...
Abstract Recent discovery of the half quantized thermal Hall conductivity in $$\alpha$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>α</mml:mi> </mml:math> -RuCl $${}_{3}$$ <mml:msub> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> , a candidate material for Kitaev spin liquid, suggests presence highly entangled quantum state external magnetic fields. This field induced phase appears between low zig-zag order and high polarized state. Motivated by this...
We propose a theoretical model for gapless spin liquid phase that may have been observed in recent experiment on ${\mathrm{H}}_{3}{\mathrm{LiIr}}_{2}{\mathrm{O}}_{6}$. Despite the insulating and nonmagnetic nature of material, specific heat coefficient $C/T\ensuremath{\sim}1/\sqrt{T}$ zero magnetic field $C/T\ensuremath{\sim}T/{B}^{3/2}$ with finite $B$ observed. In addition, NMR relaxation rate shows $1/({T}_{1}T)\ensuremath{\sim}{(C/T)}^{2}$. Motivated by fact interlayer/in-plane lattice...
Recent experiments on the dipolar-octupolar pyrochlore compound ${\mathrm{Ce}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$ indicate that it may realize a three-dimensional quantum spin liquid (QSL). In particular, analyses of available data suggest system is in region parameter space, where so-called $\ensuremath{\pi}$-flux $U(1)$ octupolar ice (QSI) with an emergent photon could be realized. However, because far from perturbative classical regime, unclear whether ground state primarily coherent...
Recent experiments suggest a quantum spin liquid ground state in the material ${\mathrm{PbCuTe}}_{2}{\mathrm{O}}_{6}$, where $S=1/2$ moments are coupled by antiferromagnetic Heisenberg interactions into three-dimensional structure of corner sharing triangles dubbed hyper-hyperkagome lattice. It exhibits richer connectivity, and thus likely stronger geometric frustration, than relatively well studied hyperkagome Here, we investigate possible liquids magnet using complex fermion mean field...
There has been a great interest in magnetic field induced quantum spin liquids Kitaev magnets after the discovery of neutron scattering continuum and half quantized thermal Hall conductivity material $\alpha$-RuCl$_3$. In this work, we provide semiclassical analysis relevant theoretical models on large system sizes, compare results to previous studies with small sizes. We find series competing orders fairly unit cells at intermediate fields, which are most likely missed by approaches. show...
Geometric frustration in spin systems offers potential routes to realize unusual phases of matter. The authors consider emergent quantum liquids interacting $S=1/2$ moments on the pyrochlore lattice with a breathing anisotropy, where two inequivalent sets tetrahedra are present. They classify possible ${\mathbb{Z}}_{2}$ and U(1) this system find small number physically motivated candidates. In particular, degenerate identified for antiferromagnetic Heisenberg model. degeneracy is robust...
While the existence of a magnetic field induced quantum spin liquid in Kitaev magnets remains under debate, its topological properties often extend to proximal phases where they can lead unusual behaviors both fundamental and applied interests. Subjecting generic nearest-neighbor model sufficiently strong in-plane field, we study resulting polarized phase associated magnon excitations. In contrast case an out-of-plane band topology is enforced by symmetry, find that it possible for...
Abstract Recently, the observation of large thermal Hall conductivities in correlated insulators with no apparent broken symmetry has generated immense interest and debates on underlying ground states. Here, considering frustrated magnets bond-dependent interactions, which are realized so-called Kitaev materials, we theoretically demonstrate that a conductivity can originate from classical state without any magnetic order. We discover liquid vortices, inhomogeneous spin textures embedded...
Abstract A recent inelastic neutron scattering experiment on the pyrochlore magnet Yb 2 Ti O 7 uncovers an unusual continuum in spin excitation spectrum despite splayed ferromagnetic order ground state. While there exist well defined wave excitations at high magnetic fields, one magnon modes and two start to strongly overlap upon decreasing field, eventually they become zero field. Motivated by these observations, we investigate possible emergence of a magnetically ordered state with...
Recently, thermal Hall effect has been observed in the paramagnetic state of volborthite, which consists distorted kagome layers with $S=1/2$ local moments. Despite appearance magnetic order below $1\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, response to external field and unusual properties above $1\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ suggest possible realization exotic quantum phases. Motivated by these discoveries, we investigate spin liquid phases fermionic spinon excitations a...
The Kagome-lattice-based material, volborthite, ${\mathrm{Cu}}_{3}{\mathrm{V}}_{2}{\mathrm{O}}_{7}{(\mathrm{OH})}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}2{\mathrm{H}}_{2}\mathrm{O}$, has been considered as a promising platform for discovery of unusual quantum ground states due to the frustrated nature spin interaction. We explore possible liquid and magnetically ordered phases in two-dimensional nonsymmorphic lattice, which is described by plane group $p2gg$, consistent with spatial...
The emergence of scalar Higgs-type amplitude modes in systems where symmetry is spontaneously broken has been a highly successful, paradigmatic description phase transitions, with implications ranging from high-energy particle physics to low-energy condensed matter systems. Here, we uncover two successive high temperature transitions the pyrochlore magnet Nd$_2$Ru$_2$O$_7$ at $T_{\mathrm{N}} = 147$ K and $T^* 97$ K, that lead giant phonon instabilities culminate coherent excitation. This...
Motivated by recent experiments on Ce$_2$Zr$_2$O$_7$ that reveal a dynamic, liquid-like ground state, we study the nearest neighbor XYZ Hamiltonian of dipolar-octupolar pyrochlore magnets with pseudofermion functional renormalization group (PFFRG), which is numerically implemented SpinParser software. Taking interaction between octupolar components to be dominant and antiferromagnetic, map out phase diagram demarcating quantum disordered magnetically ordered states. We identify four distinct...
While the existence of a magnetic field induced quantum spin liquid in Kitaev magnets remains under debate, its topological properties often extend to proximal phases where they can lead unusual behaviors both fundamental and applied interests. Subjecting generic nearest neighbor model sufficiently strong in-plane field, we study resulting polarized phase associated magnon excitations. In contrast case an out-of-plane band topology is enforced by symmetry, find that it possible for...