Short-range Spin Correlations Research Articles

Syntheses, structures, and magnetic properties of new [Co9] cluster

A new spin-cluster compound K6BaCo9(PO4H)3(PO4)6Cl2 was synthesized by the traditional solid-phase method. The fundamental magnetic unit of the compound is a coupled [Co9] cluster, which is composed of three non-coplanar triangles. These [Co9] clusters are interconnected by phosphate groups, constructing a two-dimensional framework in the ab plane. The crystal shows the clear easy-axis anisotropy. No long-range magnetic ordering was observed down to 2 K, but there is short-range spin correlation below T = 2.45 K. The Curie-Weiss temperature is about θCW = −19.38 K for the powder sample, which indicates that the dominant exchange interaction is antiferromagnetic with strong frustration (f = |θCW|/T ≈ 10). The magnetization curve presents a likely magnetic field induced transition at μ0Hc = 1.85 T.

Dynamic and magnetic properties of excited magnons in tetragonal fcc [formula omitted]/SiO multilayer alloys

In this paper, we investigate by numerical lattice simulations the magnetic and dynamic properties of excited magnons in d transition metal alloys FexPt1−x/SiO using Green functions and second quantification techniques. The sandwich structure consists of magnetic (FePt) and non-magnetic (SiO) layers. The corresponding quantum Heisenberg Hamiltonian includes exchange interactions, magnetocrystalline anisotropy, surface anisotropy and magnetic field. The existence of the surface magnons is demonstrated by the surface creation factor η, which is in good agreement with the measured lifetime data. Surface magnons are characterized by their excitation spectrum, susceptibility of creation, creation gap, permitted band for creation, and lifetime, which are different from volume magnons properties. The susceptibility of creation analysis is compatible with experimental values, and the calculated lifetimes are in the order of femtoseconds (fs) reproducing the analytical behavior of the measured values along the lattice symmetry axis. The surface magnons are found to be more confined in time and space than those excited in volume, indicating the presence of short-range spin correlations. Magnetization per spin versus temperature is also calculated for different iron concentrations x and found to be in excellent agreement with the measured values. Also, the response of the system to an external magnetic field is shown for xFe=0.29 with various temperature values, and it agrees well with the experience.

Magnetic properties of S=12 distorted J1−J2 honeycomb lattice compound NaCuIn(PO4)2

The subtle interplay between low-dimensionality and spin correlations can lead to exotic ground states with unconventional excitations in two-dimensional honeycomb-lattice-based quantum magnets. Herein, we present the structural, magnetic, and heat capacity measurements; density functional theory $+$ Hubbard $U$ ($\mathrm{DFT}+U$) based electronic structure calculations; and quantum Monte Carlo simulations for $\mathrm{NaCuIn}{({\mathrm{PO}}_{4})}_{2}$. The structure of $\mathrm{NaCuIn}{({\mathrm{PO}}_{4})}_{2}$ consists of a well-separated, $\mathit{S}=\frac{1}{2}$ distorted ${\mathit{J}}_{1}\text{\ensuremath{-}}{\mathit{J}}_{2}$ honeycomb layer which is a combination of the magnetic couplings ${\mathit{J}}_{1}$ (forming spin dimers) and ${\mathit{J}}_{2}$ (constituting spin chains). At high temperatures, the magnetic susceptibility $\ensuremath{\chi}(T)$ follows paramagnetic behavior with a Curie-Weiss temperature ${\ensuremath{\theta}}_{\mathrm{CW}}\ensuremath{\approx}\ensuremath{-}16$ K, implying the presence of antiferromagnetic interactions. A broad maximum is observed at about $13\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ in $\ensuremath{\chi}(T)$, indicating the presence of short-range spin correlations. The quantum Monte Carlo simulations using the $\mathit{S}=\frac{1}{2}\phantom{\rule{4pt}{0ex}}{\mathit{J}}_{1}\text{\ensuremath{-}}{\mathit{J}}_{2}$ Heisenberg model on a distorted honeycomb lattice are in good agreement with the measured magnetic susceptibility data. The obtained ratio of the exchange couplings ($\frac{{\mathit{J}}_{2}}{{\mathit{J}}_{1}}$) is 2.63, which is consistent with the value obtained from our $\mathrm{DFT}+U$ calculations. The title material undergoes a magnetic long-range order at 0.4 K in the heat capacity, which is suppressed with an applied magnetic field of 10 kOe. The magnetic heat capacity data follow a linear temperature-dependent behavior well above the transition temperature, suggesting the presence of gapless excitations. The observed behavior can be attributed to the presence of low connectivity and weak magnetic frustration in this two-dimensional distorted honeycomb lattice.

Superconductivity in doped triangular Mott insulators: The roles of parent spin backgrounds and charge kinetic energy

We study the prerequisites for realizing superconductivity in doped triangular-lattice Mott insulators by considering three distinct parent spin backgrounds, i.e., ${120}^{\ensuremath{\circ}}$ antiferromagnets, quantum spin liquid, and stripy antiferromagnets, and all possible sign combinations $({\ensuremath{\tau}}_{1},{\ensuremath{\tau}}_{2})$ of nearest-neighbor hopping and next-nearest-neighbor hopping $({t}_{1},{t}_{2})$. Based on density matrix renormalization group calculations, we find that, with finite ${t}_{2}$ and specific sign combinations $({\ensuremath{\tau}}_{1},{\ensuremath{\tau}}_{2})$, the quasi-long-range superconductivity order can always be achieved, regardless of the nature of the parent spin backgrounds. Besides specific hopping signs $({\ensuremath{\tau}}_{1},{\ensuremath{\tau}}_{2})$, these superconductivity phases in triangular lattices are commonly characterized by short-ranged spin correlations and two charges per stripe. In the robust superconductivity phase realized at larger ${t}_{2}/{t}_{1}$, flipping the signs ${\ensuremath{\tau}}_{2}$ and ${\ensuremath{\tau}}_{1}$ gives rise to the stripe phase without strong pairing and a pseudogaplike phase without Cooper-pair phase coherence, respectively. Interestingly, the roles of the two hopping signs are switched at smaller ${t}_{2}/{t}_{1}$. Moreover, different sign combinations $({\ensuremath{\tau}}_{1},{\ensuremath{\tau}}_{2})$ would stabilize distinct phases including superconductivity, charge density waves, spin density waves, and pseudogaplike phases accordingly. Our findings suggest the important role of charge kinetic energy in realizing superconductivity in doped triangular-lattice Mott insulators.

Crystal structure and physical properties of layered Na[formula omitted]Fe[formula omitted]S[formula omitted

Layered iron oxysulfide Na2Fe2S2O serves as a cathode material for Na-ion batteries as well as a possible parent compound of novel superconductors. Here we report the crystal structure and physical properties on the basis of our successful synthesis of the high-purity sample. Na2Fe2S2O crystallizes in an anti-K2NiF4-type structure, which gives rise to the characteristic [Fe2S2O]2− block layers. The physical property measurements indicate that it is an antiferromagnetic insulator with a Néel temperature of TN=91.5 K and an energy gap no less than 0.43 eV. Evidence of two-dimensional short-range spin correlations above TN is given by the magnetic and specific-heat measurements. Our structural correlation analysis suggests that the Fe–S bond distance dominantly determines TN.

Unusual dynamics of spin-[formula omitted] antiferromagnets on the triangular lattice in magnetic field

We theoretically discuss dynamical properties of spin-12 Heisenberg antiferromagnet on the triangular lattice in magnetic field H. We use the recently proposed bond-operator theory which operates with quantum states of the whole magnetic unit cell containing three spins. This technique describes accurately short-range spin correlations and provides a quantitative description of elementary excitations which appear in other approaches as bound states of conventional low-energy quasiparticles (e.g., magnons). In quantitative agreement with previous numerical and analytical findings, we observe four phases with coplanar spin arrangements upon the field increasing: the three-sublattice Y-phase, the collinear “up-up-down” (UUD) state, the non-collinear V-phase, and the collinear fully polarized (FP) state. We demonstrate that apart from magnons (spin-1 quasiparticles) there are spin-0 elementary excitations in the UUD state one of which is long lived and its spectrum lies below magnon branches. This mode originates from a high-energy quasiparticle at H=0 and it produces anomalies only in the longitudinal spin correlator because longitudinal and transverse channels are separated in collinear states. All other spin-0 excitations have finite lifetime and produce visibly anomalies in the dynamical structure factor. In the V-phase, we obtain multiple short-wavelength spin excitations which have no counterparts in the semiclassical spin-wave theory. Besides, we demonstrate a highly nontrivial field evolution of quasiparticles spectra on the way from one collinear state (UUD) to another one (FP) via the non-collinear V-phase (in which the longitudinal and the transverse channels are mixed). In particular, some parts of the spin-0 branch in the UUD state become parts of the spin-1 (magnon) branch in the FP phase whereas some parts of one magnon branch turn into parts of spin-2 branch. Such evolution would be very difficult to find by any conventional analytical approach. Our results are in good agreement with neutron experimental data obtained recently in Ba3CoSb2O9, KYbSe2, and CsYbSe2.

Short-range spin order in paramagnetic AgCrSe2

Muon spin rotation (μSR) experiments were performed to directly investigate the temperature dependence of the short-range order or correlations of chromium spins in the paramagnetic phase of AgCrSe2. The detailed investigation of the μSR spectra over a wide temperature range from low to high temperatures revealed that the short-range spin correlations developed below about 184 K. It also confirmed no short-range correlation at high temperatures, which had been controversial in previous quasi-elastic neutron scattering studies. In addition, the muon spin relaxation was qualitatively changed and showed large missing asymmetry below about 89 K, where the correlation clearly implied short-range spin order. There could be a preparative phenomenon of the phase transition or an anisotropic short-range spin correlation.

Magnetic short-range order in polycrystalline SrGd2O4 and SrNd2O4 studied by reverse Monte Carlo simulations and magnetic pair-distribution function analysis

We present a study combining total-scattering powder neutron diffraction, reverse Monte Carlo simulations, and magnetic pair-distribution function analysis to deduce both the static and dynamic short-range magnetic spin correlations in two compounds of the rare-earth strontium oxides: ${\mathrm{SrGd}}_{2}{\mathrm{O}}_{4}$ and ${\mathrm{SrNd}}_{2}{\mathrm{O}}_{4}$. Both compounds exhibit a distorted honeycomb lattice which forms a set of zigzag ladders along the crystallographic $c$ axis of space group $Pnam$. Each set consists of two one-dimensional chains separated by diagonal rungs forming triangles, thus inducing a large degree of geometrical frustration due to the antiferromagnetic exchange between the magnetic ions. Significant magnetic diffuse scattering was observed well above the respective N\'eel temperatures and analyzed with reverse Monte Carlo techniques in reciprocal space. As a complementary analysis in real space we have derived the magnetic pair-distribution function for both compounds as a function of temperature. Our results clearly indicate that the individual zigzag ladders begin ordering well above ${T}_{\mathrm{N}}$ due to the dominating nearest and next-nearest interactions, long before interladder spin correlations become significant only slightly above ${T}_{\mathrm{N}}$. Additionally, for ${\mathrm{SrNd}}_{2}{\mathrm{O}}_{4}$ we find some qualitative differences between the short-range spin correlations above ${T}_{\mathrm{N}}$ and those observed in the ordered state.

Triangular Magnet Emergent from Noncentrosymmetric Sr0.94Mn0.86Te1.14O6 Single Crystals.

We report the successful growth of high-quality single crystals of Sr0.94Mn0.86Te1.14O6 (SMTO) using a self-flux method. The structural, electronic, and magnetic properties of SMTO are investigated by neutron powder diffraction (NPD), single-crystal X-ray diffraction (SCXRD), thermodynamic, and nuclear magnetic resonance techniques in conjunction with density functional theory calculations. NPD unambiguously determined octahedral (trigonal antiprismatic) coordination for all cations with the chiral space group P312 (no. 149), which is further confirmed by SCXRD data. The Mn and Te elements occupy distinct Wyckoff sites, and minor anti-site defects were observed in both sites. X-ray photoelectron spectroscopy reveals the existence of mixed valence states of Mn in SMTO. The magnetic susceptibility and specific heat data evidence a weak antiferromagnetic order at TN = 6.6 K. The estimated Curie-Weiss temperature θCW = -21 K indicates antiferromagnetic interaction between Mn ions. Furthermore, both the magnetic entropy and the 125Te nuclear spin-lattice relaxation rate showcase that short-range spin correlations persist well above the Néel temperature. Our work demonstrates that Sr0.94(2)Mn0.86(3)Te1.14(3)O6 single crystals realize a noncentrosymmetric triangular antiferromagnet.

Frustrated mixed-spin ladders: Evidence for a bond-order wave phase between rung-singlet and Haldane phases

In frustrated spin ladders the interplay of frustration and correlations leads to the familiar Haldane (H) and rung-singlet (RS) phases. The nature of the transition between these two phases is still under debate. In this paper we tackle this issue using tools of quantum information theory. We consider frustrated mixed-spin-(1, 1/2) ladders with antiferromagnetic leg, rung and diagonal couplings, and calculate various quantities, such as the entanglement entropy (EE), the Schmidt gap, and the level degeneracy of the entanglement spectrum (ES). We use two numerical techniques, the infinite time-evolving block decimation (iTEBD) and the density matrix renormalization group (DMRG). We demonstrate that there exists an intermediate phase in which the ES levels do not exhibit the characteristic degeneracies of the H and RS phases. To understand the underlying physics in this phase, we investigate short-range spin correlations along legs, rungs and diagonals and show that in this intermediate phase long-wavelength modulations occur, akin to bond order waves.

Spin liquid state in a rare-earth hyperkagome lattice

Quantum fluctuations enhanced by frustration and subtle interplay between competing degrees of freedom offer an ideal ground to realize novel states with fractional quantum numbers in quantum materials that defy standard theoretical paradigms. Quantum spin liquid (QSL) is a highly entangled state wherein frustration induced strong quantum fluctuations preclude symmetry breaking phase transitions down to zero temperature without any order parameter. Experimental realizations of QSL in quantum materials with spin dimensionality greater than one is very rare. Here, we present our thermodynamic, nuclear magnetic resonance, muon spin relaxation and inelastic neutron scattering studies of a new rare-earth hyperkagome compound Li3Yb3Te2O12 in which Yb3+ ions constitute a three dimensional spin-lattice without any detectable disorder. Our comprehensive experiments evince neither signature of magnetic ordering nor spin freezing down to 38 mK that suggest the realization of dynamic liquid-like ground state in this antiferromagnet. The ground state of this material is interpreted by a low energy Jeff = 1/2 degrees of freedom with short range spin correlations. The present results demonstrate a viable basis to explore spin-orbit driven enigmatic correlated quantum states in a new class of rare-earth based three dimensional frustrated magnets that may open new avenues in theoretical and experimental search for spin liquids.

Doped Mott insulators in the triangular-lattice Hubbard model

We investigate the evolution of the Mott insulators in the triangular lattice Hubbard Model, as a function of hole doping $\delta$ in both the strong and intermediate coupling limits. Using the advanced density matrix renormalization group (DMRG) method, at light hole doping $\delta\lesssim 10\%$, we find a significant difference between strong and intermediate couplings. Notably, at intermediate coupling an unusual metallic state emerges, with short ranged spin correlations but long ranged spin-chirality order. Moreover, no clear Fermi surface or wave-vector is observed, this chiral metal also exhibits staggered loop current, which breaks the translational symmetry. These features disappear on increasing interaction strength or on further doping. At strong coupling, the 120 degree magnetic order of the insulating magnet persists for light doping, and produces hole pockets with a well defined Fermi surface. On further doping, $\delta \approx 10\%\sim 20\%$ SDW order and coherent hole Fermi pockets are found at both strong and intermediate couplings. At even higher doping $\delta \gtrsim 20\%$, the SDW order is suppressed and the spin-singlet Cooper pair correlations are simultaneously enhanced. We also briefly comment on the strong particle-hole asymmetry of the model.

Real-space visualization of short-range antiferromagnetic correlations in a magnetically enhanced thermoelectric

Short-range magnetic correlations can significantly increase the thermopower of magnetic semiconductors, representing a noteworthy development in the decades-long effort to develop high-performance thermoelectric materials. Here, we reveal the nature of the thermopower-enhancing magnetic correlations in the antiferromagnetic semiconductor MnTe. Using magnetic pair distribution function analysis of neutron scattering data, we obtain a detailed, real-space view of robust, nanometer-scale, antiferromagnetic correlations that persist into the paramagnetic phase above the N\'eel temperature $T_{\mathrm{N}}$ = 307 K. The magnetic correlation length in the paramagnetic state is significantly longer along the crystallographic $c$ axis than within the $ab$ plane, pointing to anisotropic magnetic interactions. Ab initio calculations of the spin-spin correlations using density functional theory in the disordered local moment approach reproduce this result with quantitative accuracy. These findings constitute the first real-space picture of short-range spin correlations in a magnetically enhanced thermoelectric and inform future efforts to optimize thermoelectric performance by magnetic means.

Thermal Hall conductivity of electron-doped cuprates

Measurements of the thermal Hall conductivity in hole-doped cuprates have shown that phonons acquire chirality in a magnetic field, both in the pseudogap phase and in the Mott insulator state. The microscopic mechanism at play is still unclear. A number of theoretical proposals are being considered, including skew scattering of phonons by various defects, the coupling of phonons to spins, and a state of loop-current order with the appropriate symmetries, but more experimental information is required to constrain theoretical scenarios. Here we present our study of the thermal Hall conductivity $\kappa_{\rm {xy}}$ in the electron-doped cuprates Nd$_{2-x}$Ce$_x$CuO$_4$ and Pr$_{2-x}$Ce$_x$CuO$_4$, for dopings across the phase diagram, from $x$ = 0, in the insulating antiferromagnetic phase, up to $x$ = 0.17, in the metallic phase above optimal doping. We observe a large negative thermal Hall conductivity at all dopings, in both materials. Since heat conduction perpendicular to the CuO$_2$ planes is dominated by phonons, the large thermal Hall conductivity we observe in electron-doped cuprates for a heat current in that direction must also be due to phonons, as in hole-doped cuprates. Measurements with a heat current perpendicular to the CuO$_2$ planes confirm that phonons are responsible for this thermal Hall signal, as in hole-doped cuprates. However, the degree of chirality, measured as the ratio $|\kappa_{\rm {xy}}$ / $\kappa_{\rm {xx}} |$, where $\kappa_{\rm {xx}}$ is the longitudinal thermal conductivity, is much larger in the electron-doped cuprates. We discuss various factors that may be involved in the mechanism that confers chirality to phonons in cuprates, including short-range spin correlations.

Magnetic properties of the S = 52 anisotropic triangular chain compound Bi3FeMo2O12

Competing magnetic interactions in low-dimensional quantum magnets can lead to the exotic ground state with fractionalized excitations. Herein, we present our results on an S = 5/2 quasi-one-dimensional spin system Bi3FeMo2O12. The structure of Bi3FeMo2O12 consists of very well separated, infinite zig-zag S = 5/2 spin chains. The observation of a broad maximum around 10 K in the magnetic susceptibility suggests the presence of short-range spin correlations. Magnetic susceptibility data do not fit to S=5/2 uniform spin chain model due to the presence of 2nd nearest-neighbor coupling (J2) along with the 1st nearest-neighbor coupling J1 of the zig-zag chain. The electronic structure calculations infer that the value of J1 is comparable with J2 (J2/J1~1.1) with a negligible inter-chain interaction (J'/J ~ 0.01), implying that Bi3FeMo2O12 is a highly frustrated triangular chain system. The absence of magnetic long-range ordering down to 0.2 K is seen in the heat capacity data, despite a relatively large antiferromagnetic Curie-Weiss temperature of -40 K. The magnetic heat capacity follows nearly a linear behavior at low temperatures indicating that the S = 5/2 anisotropic triangular chain exhibits the gapless excitations.

Ground-state phase diagram of the t-t′-J model

We report results of large-scale ground-state density matrix renormalization group (DMRG) calculations on t-[Formula: see text]-J cylinders with circumferences 6 and 8. We determine a rough phase diagram that appears to approximate the two-dimensional (2D) system. While for many properties, positive and negative [Formula: see text] values ([Formula: see text]) appear to correspond to electron- and hole-doped cuprate systems, respectively, the behavior of superconductivity itself shows an inconsistency between the model and the materials. The [Formula: see text] (hole-doped) region shows antiferromagnetism limited to very low doping, stripes more generally, and the familiar Fermi surface of the hole-doped cuprates. However, we find [Formula: see text] strongly suppresses superconductivity. The [Formula: see text] (electron-doped) region shows the expected circular Fermi pocket of holes around the [Formula: see text] point and a broad low-doped region of coexisting antiferromagnetism and d-wave pairing with a triplet p component at wavevector [Formula: see text] induced by the antiferromagnetism and d-wave pairing. The pairing for the electron low-doped system with [Formula: see text] is strong and unambiguous in the DMRG simulations. At larger doping another broad region with stripes in addition to weaker d-wave pairing and striped p-wave pairing appears. In a small doping region near [Formula: see text] for [Formula: see text], we find an unconventional type of stripe involving unpaired holes located predominantly on chains spaced three lattice spacings apart. The undoped two-leg ladder regions in between mimic the short-ranged spin correlations seen in two-leg Heisenberg ladders.

Suppressed incommensurate order in swedenborgite Ca0.5Y0.5BaCo4O7

Swedenborgite Ca${}_{0.5}$Y${}_{0.5}$BaCo${}_{4}$O${}_{7}$, with geometrically frustrated kagome and triangular lattices, exhibits a disordered ground state in spite of strong antiferromagnetic coupling between the Co spins. Here, the authors perform single-crystal diffuse neutron scattering experiments to fully characterize the short-range spin correlations in this compound and determine that long-range incommensurate spin correlations are suppressed by exchange disorder. This result reveals a general correspondence between unequal interactions and incommensurate spin correlations on the swedenborgite lattice.

Magnetic structure, excitations and short-range order in honeycomb Na2Ni2TeO6

Na2Ni2TeO6 has a layered hexagonal structure with a honeycomb lattice constituted by Ni2+ and a chiral charge distribution of Na+ that resides between the Ni layers. In the present work, the antiferromagnetic (AFM) transition temperature of Na2Ni2TeO6 is confirmed at T N ≈ 27 K, and further, it is found to be robust up to 8 T magnetic field and 1.2 GPa external pressure; and, without any frequency-dependence. Slight deviations from nominal Na-content (up to 5%) does not seem to influence the magnetic transition temperature, T N. Isothermal magnetization curves remain almost linear up to 13 T. Our analysis of neutron diffraction data shows that the magnetic structure of Na2Ni2TeO6 is faithfully described by a model consisting of two phases described by the commensurate wave vectors , and , with an additional short-range order component incorporated in to the latter phase. Consequently, a zig-zag long-range ordered magnetic phase of Ni2+ results in the compound, mixed with a short-range ordered phase, which is supported by our specific heat data. Theoretical computations based on density functional theory predict predominantly in-plane magnetic exchange interactions that conform to a J 1–J 2–J 3 model with a strong J 3 term. The computationally predicted parameters lead to a reliable estimate for T N and the experimentally observed zig-zag magnetic structure. A spin wave excitation in Na2Ni2TeO6 at E ≈ 5 meV at T = 5 K is mapped out through inelastic neutron scattering experiments, which is reproduced by linear spin wave theory calculations using the J values from our computations. Our specific heat data and inelastic neutron scattering data strongly indicate the presence of short-range spin correlations, at T > T N, stemming from incipient AFM clusters.

Unusual excitations and double-peak specific heat in a bond-alternating spin-1 K−Γ chain

One-dimensional gapped phases that avoid any symmetry breaking have drawn enduring attention. In this paper, we study such phases in a bond-alternating spin-1 $K$-$\Gamma$ chain built of a Kitaev ($K$) interaction and an off-diagonal $\Gamma$ term. In the case of isotropic bond strength, a Haldane phase, which resembles the ground state of a spin-$1$ Heisenberg chain, is identified in a wide region. A gapped Kitaev phase situated at dominant ferromagnetic and antiferromagnetic Kitaev limits is also found. The Kitaev phase has extremely short-range spin correlations and is characterized by finite $\mathbb{Z}_2$-valued quantities on bonds. Its lowest entanglement spectrum is unique, in contrast to the Haldane phase whose entanglement spectrum is doubly degenerate. In addition, the Kitaev phase shows a double-peak structure in the specific heat at two different temperatures. In the pure Kitaev limit, the two peaks are representative of the development of short-range spin correlation at $T_h \simeq 0.5680$ and the freezing of $\mathbb{Z}_2$ quantities at $T_l \simeq 0.0562$, respectively. By considering bond anisotropy, regions of Haldane phase and Kitaev phase are enlarged, accompanied by the emergence of dimerized phases and three distinct magnetically ordered states.

Probing the interplay between lattice dynamics and short-range magnetic correlations in CuGeO3 with femtosecond RIXS

Investigations of magnetically ordered phases on the femtosecond timescale have provided significant insights into the influence of charge and lattice degrees of freedom on the magnetic sub-system. However, short-range magnetic correlations occurring in the absence of long-range order, for example in spin-frustrated systems, are inaccessible to many ultrafast techniques. Here, we show how time-resolved resonant inelastic X-ray scattering (trRIXS) is capable of probing such short-ranged magnetic dynamics in a charge-transfer insulator through the detection of a Zhang–Rice singlet exciton. Utilizing trRIXS measurements at the O K-edge, and in combination with model calculations, we probe the short-range spin correlations in the frustrated spin chain material CuGeO3 following photo-excitation, revealing a strong coupling between the local lattice and spin sub-systems.