Long-range Spin Research Articles

Dynamical Hadron Formation in Long-Range Interacting Quantum Spin Chains

The study of confinement in quantum spin chains has seen a large surge of interest in recent years. It is not only important for understanding a range of effective one-dimensional condensed matter realizations, but also shares some of the non-perturbative physics with quantum chromodynamics (QCD) which makes it a prime target for current quantum simulation efforts. In analogy with QCD, the confinement-induced two-particle boundstates that appear in these models are dubbed mesons. Here, we study scattering events due to meson collisions in a quantum spin chain with long-range interactions such that two mesons have an extended interaction. We show how novel hadronic boundstates, e.g. with four constituent particles akin to tetraquarks, may form dynamically in fusion events. In a natural collision their signal is weak as elastic meson scattering dominates. However, we propose two controllable protocols which allow for a clear observation of dynamical hadron formation. We discuss how this physics can be simulated in trapped ion or Rydberg atom set-ups.

Tuning between Continuous Time Crystals and Many-Body Scars in Long-Range XYZ Spin Chains.

Persistent oscillatory dynamics in nonequilibrium many-body systems is a tantalizing manifestation of ergodicity breakdown that continues to attract much attention. Recent works have focused on two classes of such systems: discrete time crystals and quantum many-body scars (QMBS). While both systems host oscillatory dynamics, its origin is expected to be fundamentally different: discrete time crystal is a phase of matter which spontaneously breaks the Z_{2} symmetry of the external periodic drive, while QMBS span a subspace of nonthermalizing eigenstates forming an su(2) algebra representation. Here, we ask a basic question: is there a physical system that allows us to tune between these two dynamical phenomena? In contrast to much previous work, we investigate the possibility of a continuous time crystal (CTC) in undriven, energy-conserving systems exhibiting prethermalization. We introduce a long-range XYZ spin model and show that it encompasses both a CTC phase as well as QMBS. We map out the dynamical phase diagram using numerical simulations based on exact diagonalization and time-dependent variational principle in the thermodynamic limit. We identify a regime where QMBS and CTC order coexist, and we discuss experimental protocols that reveal their similarities as well as key differences.

Photoluminescence Path Bifurcations by Spin Flip in Two-Dimensional CrPS4.

Ultrathin layered crystals of coordinated chromium(III) are promising not only as two-dimensional (2D) magnets but also as 2D near-infrared (NIR) emitters due to long-range spin correlation and efficient transition between high- and low-spin excited states of Cr3+ ions. In this study, we report on the dual-band NIR photoluminescence (PL) of CrPS4 and show that its excitonic emission bifurcates into fluorescence and phosphorescence depending on thickness, temperature, and defect density. In addition to the spectral branching, the biexponential decay of PL transients, also affected by the three factors, could be well described within a three-level kinetic model for Cr(III). In essence, the PL bifurcations are governed by activated reverse intersystem crossing from the low- to high-spin states, and the transition barrier becomes lower for thinner 2D samples because of surface-localized defects. Our findings can be generalized to 2D solids of coordinated metals and will be valuable in realizing groundbreaking magneto-optic functions and devices.

Spin-orbit coupling controlled ground states in the double perovskite iridates A2BIrO6 ( A= Ba, Sr; B= Lu, Sc)

Iridates with the $5{d}^{4}$ electronic configuration have attracted recent interest due to reports of magnetically ordered ground states despite longstanding expectations that their strong spin-orbit coupling would generate a $J=0$ electronic ground state for each ${\mathrm{Ir}}^{5+}$ ion. The major focus of prior research has been on the double perovskite iridates ${\mathrm{Ba}}_{2}{\mathrm{YIrO}}_{6}$ and ${\mathrm{Sr}}_{2}{\mathrm{YIrO}}_{6}$, where the nature of the ground states (i.e., ordered vs nonmagnetic) is still controversial. Here, we present neutron powder diffraction, high-energy-resolution fluorescence-detected x-ray absorption spectroscopy (HERFD-XAS), resonant inelastic x-ray scattering (RIXS), magnetic susceptibility, and muon spin relaxation data on the related double perovskite iridates ${\mathrm{Ba}}_{2}{\mathrm{LuIrO}}_{6}, {\mathrm{Sr}}_{2}{\mathrm{LuIrO}}_{6}, {\mathrm{Ba}}_{2}{\mathrm{ScIrO}}_{6}$, and ${\mathrm{Sr}}_{2}{\mathrm{ScIrO}}_{6}$ that enable us to gain a general understanding of the electronic and magnetic properties for this family of materials. Our HERFD-XAS and RIXS measurements establish $J=0$ electronic ground states for the ${\mathrm{Ir}}^{5+}$ ions in all cases, with similar values for Hund's coupling ${J}_{\mathrm{H}}$ and the spin-orbit coupling constant ${\ensuremath{\lambda}}_{\mathrm{SOC}}$. Our bulk susceptibility and muon spin relaxation data find no evidence for long-range magnetic order or spin freezing, but they do exhibit weak magnetic signals that are consistent with extrinsic local moments. Our results indicate that the large ${\ensuremath{\lambda}}_{\mathrm{SOC}}$ is the key driving force behind the electronic and magnetic ground states realized in the $5{d}^{4}$ double perovskite iridates, which agrees well with conventional wisdom.

Quantum spin liquid with emergent chiral order in the triangular-lattice Hubbard model

The interplay between spin frustration and charge fluctuation gives rise to an exotic quantum state in the intermediate-interaction regime of the half-filled triangular-lattice Hubbard model, while the nature of the state is under debate. Using the density matrix renormalization group with SU(2)$_{\rm{spin}} \otimes $U(1)$_{\rm{charge}}$ symmetries implemented, we study the triangular-lattice Hubbard model defined on the long cylinder geometry up to circumference $W=6$. A gapped quantum spin liquid, with on-site interaction $9 \lesssim U / t \lesssim 10.75$, is identified between the metallic and the antiferromagnetic Mott insulating phases. In particular, we find that this spin liquid develops a robust long-range spin scalar-chiral correlation as the system length $L$ increases, which unambiguously unveils the spontaneous time-reversal symmetry breaking. In addition, the degeneracy of the entanglement spectrum supports symmetry fractionalization and spinon edge modes in the obtained ground state. The possible origin of chiral order in this intermediate spin liquid and its relation to the rotonlike excitations have also been discussed.

Quantum critical spin-liquid-like behavior in the S=12 quasikagome-lattice compound CeRh1−xPdxSn investigated using muon spin relaxation and neutron scattering

We present the results of muon spin relaxation ($\ensuremath{\mu}\mathrm{SR}$) and neutron scattering on the Ce-based quasikagome lattice ${\mathrm{CeRh}}_{1\ensuremath{-}x}{\mathrm{Pd}}_{x}\mathrm{Sn}$ ($x=0.1$ to 0.75). Our zero-field (ZF) $\ensuremath{\mu}\mathrm{SR}$ results reveal the absence of both static long-range magnetic order and spin freezing down to 0.05 K in the single-crystal sample of $x=0.1$. The weak temperature-dependent plateaus of the dynamic spin fluctuations below 0.2 K in ZF-$\ensuremath{\mu}\mathrm{SR}$ together with its longitudinal-field (LF) dependence between 0 and 3 kG indicate the presence of dynamic spin fluctuations persisting even at $T=0.05\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ without static magnetic order. On the other hand, the magnetic specific heat divided by temperature ${C}_{\text{4f}}/T$ increases as $\ensuremath{-}\text{log}T$ on cooling below 0.9 K, passes through a broad maximum at 0.13 K, and slightly decreases on further cooling. The ac susceptibility also exhibits a frequency-independent broad peak at 0.16 K, which is prominent with an applied field $H$ along the $c$ direction. We, therefore, argue that such a behavior for $x=0.1$ [namely, a plateau in spin relaxation rate ($\ensuremath{\lambda}$) below 0.2 K and a linear $T$ dependence in ${C}_{\text{4f}}$ below 0.13 K] can be attributed to a metallic spin-liquid-like ground state near the quantum critical point in the frustrated Kondo lattice. The LF-$\ensuremath{\mu}\mathrm{SR}$ study suggests that the out of kagome plane spin fluctuations are responsible for the spin-liquid (SL) behavior. Low-energy inelastic neutron scattering (INS) of $x=0.1$ reveals gapless magnetic excitations, which are also supported by the behavior of ${C}_{\text{4f}}$ proportional to ${T}^{1.1}$ down to 0.06 K. Our high-energy INS study shows very weak and broad scattering in $x=0$ and 0.1, which transforms into well-localized crystal-field excitations with increasing $x$. The ZF-$\ensuremath{\mu}\mathrm{SR}$ results for the $x=0.2$ polycrystalline sample exhibit similar behavior to that of $x=0.1$. A saturation of $\ensuremath{\lambda}$ below 0.2 K suggests a spin-fluctuating SL ground state down to 0.05 K. The ZF-$\ensuremath{\mu}\mathrm{SR}$ results for the $x=0.5$ sample are interpreted as a long-range antiferromagnetic (AFM) ground state below ${T}_{\text{N}}=0.8\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, in which the AFM interaction of the enlarged moments probably overcomes the frustration effect. The long-range AFM ordering is also supported by the evolution of magnetic Bragg peaks in $x=0.75$ sample observed below 5 K in the neutron diffraction data.

Nonlocality of Electrically-Induced Spin Accumulation in Chiral Metals

Spin accumulation induced by an electric field in chiral electron system is investigated based on a linear response theory. It is shown that the spin response function has a spatially uniform component due to the chiral angular momentum generation effect, resulting in a nonlocal spin generation. The result suggests a scenario for nonlocal long-range spin transport in chiral metals reported experimentally recently.

Spin excitations in the quantum dipolar magnet Yb(BaBO3)3

We report results of magnetization, specific-heat and muon-spin relaxation measurements on single crystals of disorder-free Yb$^{3+}$ triangular lattice Yb(BaBO$_3$)$_3$. The magnetization experiments show anisotropic magnetic properties with Curie-Weiss temperatures $\theta_{\perp}=-1.40$~K ($H \perp c$) and $\theta_{\parallel}=-1.16$~K ($H \parallel c$) determined from low temperature data. The absence of both long-range antiferromagnetic order and spin freezing is confirmed down to 0.27 K at zero field. A two-level Schottky anomaly due to the opening of the ground-state Kramers doublet is observed from the low-temperature specific-heat measurements when the applied magnetic fields $\mu_0H >0.7$~T. At zero field, the increase of both $C_{\rm mag}/T$ and the muon spin relaxation rate $\lambda$ below 1~K is due to the electronic spin excitations, which often exist in quantum magnets where dipole-dipole interaction creates an anisotropy of magnetic properties. The spin excitation is also supported by the unusual maximum of field dependence of $\lambda$ due to the field-induced increase of the density of excitations. We argue that dipolar interaction is dominant and induces the spin dynamics in the quantum magnet Yb(BaBO$_3$)$_3$.

Entanglement diagnostics for efficient VQA optimization

We consider information spreading measures in randomly initialized variational quantum circuits and introduce entanglement diagnostics for efficient variational quantum/classical computations. We establish a robust connection between entanglement measures and optimization accuracy by solving two eigensolver problems for Ising Hamiltonians with nearest-neighbor and long-range spin interactions. As the circuit depth affects the average entanglement of random circuit states, the entanglement diagnostics can identify a high-performing depth range for optimization tasks encoded in local Hamiltonians. We argue, based on an eigensolver problem for the Sachdev–Ye–Kitaev model, that entanglement alone is insufficient as a diagnostic to the approximation of volume-law entangled target states and that a large number of circuit parameters is needed for such an optimization task.

Spin-Ruijsenaars, q-Deformed Haldane–Shastry and Macdonald Polynomials

We study the q-analogue of the Haldane–Shastry model, a partially isotropic (xxz-like) long-range spin chain that by construction enjoys quantum-affine (really: quantum-loop) symmetries at finite system size. We derive the pairwise form of the Hamiltonian, found by one of us building on work of D. Uglov, via ‘freezing’ from the affine Hecke algebra. To this end we first obtain explicit expressions for the spin-Macdonald operators of the (trigonometric) spin-Ruijsenaars model. Through freezing these give rise to the higher Hamiltonians of the spin chain, including another Hamiltonian of the opposite ‘chirality’. The sum of the two chiral Hamiltonians has a real spectrum also when |mathsf {q}|=1, so in particular when q is a root of unity. For generic mathsf {q} the eigenspaces are known to be labelled by ‘motifs’. We clarify the relation between these patterns and the corresponding degeneracies (multiplicities) in the crystal limit textsf {q}rightarrow infty . For each motif we obtain an explicit expression for the exact eigenvector, valid for generic q, that has (‘pseudo’ or ‘l-’) highest weight in the sense that, in terms of the operators from the monodromy matrix, it is an eigenvector of A and D and annihilated by C. It has a simple component featuring the ‘symmetric square’ of the q-Vandermonde polynomial times a Macdonald polynomial—or more precisely its quantum spherical zonal special case. All other components of the eigenvector are obtained from this through the action of the Hecke algebra, followed by ‘evaluation’ of the variables to roots of unity. We prove that our vectors have highest weight upon evaluation. Our description of the exact spectrum is complete. The entire model, including the quantum-loop action, can be reformulated in terms of polynomials. Our main tools are the Y-operators from the affine Hecke algebra. From a more mathematical perspective the key step in our diagonalisation is as follows. We show that on a subspace of suitable polynomials the first M ‘classical’ (i.e. no difference part) Y-operators in N variables reduce, upon evaluation as above, to Y-operators in M variables with parameters at the quantum zonal spherical point.

Signature of a randomness-driven spin-liquid state in a frustrated magnet

Collective behaviour of electrons, frustration induced quantum fluctuations and entanglement in quantum materials underlie some of the emergent quantum phenomena with exotic quasi-particle excitations that are highly relevant for technological applications. Herein, we present our thermodynamic and muon spin relaxation measurements, complemented by ab initio density functional theory and exact diagonalization results, on the recently synthesized frustrated antiferromagnet Li4CuTeO6, in which Cu2+ ions (S = 1/2) constitute disordered spin chains and ladders along the crystallographic [101] direction with weak random inter-chain couplings. Our thermodynamic experiments detect neither long-range magnetic ordering nor spin freezing down to 45 mK despite the presence of strong antiferromagnetic interaction between Cu2+ moments leading to a large effective Curie-Weiss temperature of − 154 K. Muon spin relaxation results are consistent with thermodynamic results. The temperature and magnetic field scaling of magnetization and specific heat reveal a data collapse pointing towards the presence of random-singlets within a disorder-driven correlated and dynamic ground-state in this frustrated antiferromagnet.

Fractional spin excitations and conductance in the spiral-staircase Heisenberg ladder

We investigate theoretically the spiral staircase Heisenberg spin-$1/2$ ladder in the presence of antiferromagnetic long-range spin interactions and a uniform magnetic field. As a special case we also consider the Kondo necklace model. If the magnetizations of the two chains forming the ladder satisfy a certain resonance condition, involving interchain couplings as perturbations, the system is in a partially gapped magnetic phase hosting excitations characterized by fractional spins, whose values can be changed by the magnetic field. We show that these fractional spin excitations can be probed by spin currents in a transport setup with a spin conductance that reveals the fractionalized spin. In some special cases, the spin conductance reaches universal values in units of $(g\mu_B)^2/h$, where $g$ is the $g$-factor, $\mu_B$ the Bohr magneton, and $h$ the Planck constant. We obtain our results with the help of bosonization and numerical density matrix renormalization group methods.

The reservoir learning power across quantum many-body localization transition

Harnessing the quantum computation power of the present noisy-intermediate-size-quantum devices has received tremendous interest in the last few years. Here we study the learning power of a one-dimensional long-range randomly-coupled quantum spin chain, within the framework of reservoir computing. In time sequence learning tasks, we find the system in the quantum many-body localized (MBL) phase holds long-term memory, which can be attributed to the emergent local integrals of motion. On the other hand, MBL phase does not provide sufficient nonlinearity in learning highly-nonlinear time sequences, which we show in a parity check task. This is reversed in the quantum ergodic phase, which provides sufficient nonlinearity but compromises memory capacity. In a complex learning task of Mackey-Glass prediction that requires both sufficient memory capacity and nonlinearity, we find optimal learning performance near the MBL-to-ergodic transition. This leads to a guiding principle of quantum reservoir engineering at the edge of quantum ergodicity reaching optimal learning power for generic complex reservoir learning tasks. Our theoretical finding can be readily tested with present experiments.

Long-Range Intramolecular Spin Coupling through a Redox-Active Bridge upon Stepwise Oxidations: Control and Effect of Metal Ions.

Dinickel(II) and dicopper(II) porphyrin dimers have been constructed in which two metalloporphyrin units are widely separated by a long unconjugated dipyrrole bridge. Two macrocycles are aligned somewhat orthogonally to each other, while oxidation of the bridge generates a fully π-conjugated butterfly-like structure, which, in turn, upon stepwise oxidations by stronger oxidants result in the formation of the corresponding one- and two-electron-oxidized species exhibiting unusual long-range charge/radical delocalization to produce intense absorptions in the near-infrared (NIR) region and electron paramagnetic resonance (EPR) signals of a triplet state due to interaction between the unpaired spins on the Cu(II) ions. Although the two metal centers have a large physical separation through the bridge (more than 16 Å), they share electrons efficiently between them, behaving as a single unit rather than two independent centers. Detailed UV-vis-NIR, electrospray ionization mass spectrometry, IR, variable-temperature magnetic study, and EPR spectroscopic investigations along with X-ray structure determination of unconjugated, conjugated, and one electron-oxidized complexes have been exploited to demonstrate the long-range electronic communication through the bridge. The experimental observations are also supported by density functional theory (DFT) and time-dependent DFT calculations. The present study highlights the crucial roles played by a redox-active bridge and metal in controlling the long-range electronic communication.

Supercurrent diode effect, spin torques, and robust zero-energy peak in planar half-metallic trilayers

We consider trilayer ${\mathrm{F}}_{1}{\mathrm{F}}_{2}{\mathrm{F}}_{3}$ Josephson junctions that are finite in two dimensions and have arbitrary magnetizations in each ferromagnet ${\mathrm{F}}_{i}\phantom{\rule{0.28em}{0ex}}(i=1,2,3)$. The trilayers are sandwiched between two $s$-wave superconductors with a macroscopic phase difference $\mathrm{\ensuremath{\Delta}}\ensuremath{\varphi}$. Our results reveal that when the magnetizations have three orthogonal components, a supercurrent can flow at $\mathrm{\ensuremath{\Delta}}\ensuremath{\varphi}=0$. With our generalized theoretical and numerical techniques, we study the planar spatial profiles and $\mathrm{\ensuremath{\Delta}}\ensuremath{\varphi}$ dependencies of the charge supercurrents, spin supercurrents, spin torques, and density of states. Remarkably, upon increasing the magnetization strength in the central ferromagnet layer up to the half-metallic limit, the self-biased current and induced second harmonic component become dramatically enhanced while the critical supercurrent reaches its maximum value. Additionally, for a broad range of exchange-field strengths and orientations, the ground state of the system can be tuned to an arbitrary phase difference ${\ensuremath{\varphi}}_{0}$. For intermediate exchange-field strengths in the middle layer ${\mathrm{F}}_{2}$, a ${\ensuremath{\varphi}}_{0}$ state can arise that creates a superconducting diode effect, whereby $\mathrm{\ensuremath{\Delta}}\ensuremath{\varphi}$ can be tuned to create a one-way dissipationless current flow. The spin currents and effective magnetic moments reveal a long-ranged spin torque in the half-metallic phase. Moreover, the density of states unveils the emergence of zero-energy peaks for the mutually orthogonal magnetization configurations. Our results suggest that this simple trilayer Josephson junction can be an excellent candidate for producing experimentally accessible signatures for long-ranged self-biased supercurrents and supercurrent diode effects.

Carrier Doping Physics of Rare Earth Perovskite Nickelates RENiO3

The family of rare earth (RE) nickelate perovskites RENiO3 has emerged over the past two decades as an important platform for quantum matter physics and advanced applications. The parent compounds from this family are strongly correlated insulators or metals, in most cases with long-range spin order. In the past few years, carrier doping has been achieved using different approaches and has been proven to be a powerful tuning parameter for the microscopic properties and collective macroscopic states in RENiO3 compounds. In particular, a series of recent studies has shown that carrier doping can be responsible for dramatic but reversible changes in the long-range electronic and magnetic properties, underscoring the potential for use of nickelates in advanced functional devices. In this review, we discuss the recent advancements in our description, understanding and application of electron-doped rare earth nickelates. We conclude with a discussion of the developments and outlook for harnessing the quantum functional properties of nickelates in novel devices for sensing and neuromorphic computation.

How Coordinate Bethe Ansatz Works for Inozemtsev Model

Three decades ago, Inozemtsev found an isotropic long-range spin chain with elliptic pair potential that interpolates between the Heisenberg and Haldane-Shastry (HS) spin chains while admitting an exact solution throughout, based on a connection with the elliptic quantum Calogero-Sutherland model. Though Inozemtsev's spin chain is widely believed to be quantum integrable, the underlying algebraic reason for its exact solvability is not yet well understood. As a step in this direction we refine Inozemtsev's `extended coordinate Bethe ansatz' and clarify various aspects of the model's exact spectrum and its limits. We identify quasimomenta in terms of which the $M$-particle energy is close to being (functionally) additive, as one would expect from the limiting models; our expression is additive iff the energy of the elliptic Calogero-Sutherland system is so. This enables us to rewrite the energy and Bethe-ansatz equations on the elliptic curve, turning the spectral problem into a rational problem as might be expected for an isotropic spin chain. We treat the $M=2$ particle sector and its limits in detail. We identify an $S$-matrix that is independent of positions. We show that the Bethe-ansatz equations reduce to those of Heisenberg in one limit and give rise to the `motifs' of HS in the other limit. We show that, as the interpolation parameter changes, the `scattering states' from Heisenberg become Yangian highest-weight states for HS, while bound states become ($\mathfrak{sl}_2$-highest weight versions of) affine descendants of the magnons from $M=1$. For bound states we find a generalisation of the known equation for the `critical length' for the Heisenberg spin chain. We discuss completeness for $M=2$ by passing to the elliptic curve. Our review of the two-particle sectors of the Heisenberg and HS spin chains may be of independent interest.

Nonthermal breaking of magnetic order via photogenerated spin defects in the spin-orbit coupled insulator Sr3Ir2O7

In Mott insulators the evolution of antiferromagnetic order to superconducting or charge-density-wave-like states upon chemical doping underpins the control of quantum phases. Photo-doping can induce similar transitions on the ultrafast timescale, however the response of the spin system has remained elusive. Here, we use 4D-ultrafast optical spectroscopy to extract quantitative magnetic dynamics in the spin-orbit coupled Mott insulator Sr3Ir2O7. We demonstrate that light can non-thermally melt long-range spin order. At low fluences magnetic order recovers within 1 ps despite demagnetization of roughly 50%. However, high fluences induce a crossover to a long-lived demagnetized state without increasing the lattice temperature. We show that the generation of photo-induced spin defects enables a mechanism that stabilizes the demagnetized state which could help expose new transient phases.

Real-space observation of incommensurate spin density wave and coexisting charge density wave on Cr (001) surface

In itinerant magnetic systems, a spin density wave (SDW) state can be induced by Fermi surface nesting and electron-electron interaction. It may intertwine with other orders such as charge density wave (CDW), while their relation is still yet to be understood. Here via spin-polarized scanning tunneling microscopy, we directly observed long-range spin modulation on Cr(001) surface, which corresponds to the well-known incommensurate SDW of bulk Cr. It displays 6.0 nm in-plane period and anti-phase behavior between adjacent (001) planes. Meanwhile, we simultaneously observed the coexisting CDW with half the period of SDW. Such SDW/CDW have highly correlated domain structures and are in-phase. Surprisingly, the CDW displays a contrast inversion around a density-of-states dip at −22 meV, indicating an anomalous CDW gap opened below EF. These observations support that the CDW is a secondary order driven by SDW. Our work is not only a real-space characterization of incommensurate SDW, but also provides insights on how SDW and CDW coexist.

Bound state dynamics in the long-range spin- 12 XXZ model

Experimental platforms based on trapped ions, cold molecules, and Rydberg atoms have made possible the investigation of highly-nonlocal spin-${1/2}$ Hamiltonians with long-range couplings. Here, we study the effects of such non-local couplings in the long-range spin-${1/2}$ XXZ Heisenberg Hamiltonian. We calculate explicitly the two-spin energy spectrum, which describes all possible energetic configurations of two spins pointing in a specific direction embedded in a background of spins with opposite orientation. For fast decay of the spin-spin couplings, we find that the two-spin energy spectrum is characterized by well-defined discrete values, corresponding to bound states, separated by a set of continuum states describing the scattering region. In the deep long-range regime instead, the bound states disappear as they get incorporated by the scattering region. The presence of two-spin bound states results to be crucial to determine both two- and many-spin dynamics. On one hand, radically different two-spin spreadings can be observed by tuning the decay of the spin couplings. On the other hand, two-spin bound states enable the dynamical stabilization of effective antiferromagnetic states in the presence of ferromagnetic couplings. Finally, we propose a novel scheme based on a trapped-ion quantum simulator to experimentally realize the long-range XXZ model and to study its out-of-equilibrium properties.