We report a systematic study of the magnetic and ferroelectric properties of Co3TeO6 single crystals under pulsed magnetic fields up to 60 T, revealing pronounced anisotropic magnetoelectric coupling and novel ferroelectric phenomena. For H//a, in addition to a low-field spin-flop transition at Ha1 16.7 T, two additional metamagnetic transitions occur at Ha2 18.3 T and Ha3 57.6 T, which correlate with a distinct new ferroelectric phase exhibiting anomalous polarization reversal. An intriguing characteristic of this reversal is the formation of a large "oo"-shaped hysteresis loop, arising from polarization sign reversal during the H-falling sweep relative to the H-rising sweep. This ferroelectric response is highly dependent on the field-sweep history, indicating complex magnetoelectric behaviors in the system. In the case of H//b, successive metamagnetic transitions are observed at Hb1 6.9 T, Hb2 11.5 T, Hb3 21.2 T, and Hb4 35.8 T, with an additional transition at higher critical magnetic fields (Hb5) above 10 K. Each transition corresponds to distinct ferroelectric phases, which exhibit varying responses to the applied bias electric field (E). In particular, the high-field ferroelectric phase above Hb4 demonstrates a robust memory effect, where both the direction and magnitude of electric polarization are retained across successive pulses of-E and +E. This suggests that the pinning of ferroelectric domain walls may prevent polarization reversal under opposing bias fields. Complementary magnetostriction measurements support the magnetization results and reveal spin-lattice coupling. Based on these comprehensive experimental findings, we construct the magnetic-field-temperature phase diagrams and investigate the underlying origin of magnetoelectric coupling in Co3TeO6. Our results offer valuable insights into high-field-induced ferroelectric phases and unusual magnetoelectric effects in noncollinear multiferroic systems.

The dynamics of phase boundaries, such as superconducting/normal (S/N) interfaces in type-I superconductors, are typically obscured in conventional magnetic measurements, which are dominated by surface barriers and over-damped flux processes. Here, we employ ac magnetostriction as a sensitive probe to reveal the distinct bulk dynamics of these domain walls in the intermediate state of lead. In contrast to the Debye-type relaxation observed in magnetic susceptibility, we discover a pronounced quasiresonant response characterized by a sign reversal of the imaginary component and a non-monotonic evolution of the real part with frequency. We attribute this behavior to the collective oscillations of S/N interfaces driven by eddy currents generated within the normal domains. This work uncovers a fundamental dynamical channel in superconducting modulated phases and establishes ac magnetostrictive coefficient as a powerful tool for probing hidden interface physics.

Abstract The exploration of emergent quantum phases driven by the interplay of spin–orbit coupling (SOC) and electronic correlation remains a central theme in materials science and solid chemistry. Herein, we report the topotactic synthesis and physical properties of NiIrO3, the first honeycomb iridate to incorporate 3d magnetic ions into the interlayer lattice. Structural investigations reveal an ilmenite-type R-3 structure, featuring alternating edge-sharing NiO6 and IrO6 honeycomb layers connected via unusually short face-sharing Ni–Ir dimers. Unlike the low-temperature antiferromagnetic states typical of conventional honeycomb iridates, NiIrO3 exhibits robust long-range ferrimagnetic order below a remarkably high transition temperature of 213 K, accompanied by a spontaneous positive magnetoresistance. Most strikingly, the synergistic interplay among the strong SOC of 5d Ir4+ ions, severe structural distortions, and intense 3d-5d orbital hybridization breaks local symmetries, driving an exceptionally large uniaxial magnetocrystalline anisotropy energy of 32.2 meV/f.u. This extreme Ising-like anisotropy underpins a record-breaking giant coercive field exceeding 17.3 T at 4.2 K. This work not only establishes topotactic chemistry as a powerful tool for engineering 3d–5d orbital hybridizations but also positions NiIrO3 as a compelling material platform for developing high-density magnetic memory and low-power spintronic devices.

The realization of unconventional quantum phases in frustrated and spin-orbit coupled materials remains at the forefront of quantum materials research. Here we report the synthesis and discovery of NiIrO3, the first honeycomb iridate with coupled 3d-5d magnetic sublattices, through a soft topotactic reaction. Structural analysis reveals an ilmenite-type stacking of edge-sharing NiO6 and IrO6 octahedral honeycomb sublattices in a Kitaev geometry. Comprehensive magnetic and electrical transport measurements unveil its long-range ferrimagnetic order below 213 K, which is in sharp contrast to the predominantly antiferromagnetic order in the known honeycomb iridates. Notably, the titled compound displays an exceptionally large magnetocrystalline anisotropy energy of 32.2 meV/f.u. and a giant coercivity with coercive field exceeding 17.3 T below 4.2 K, both ranking among the highest observed in iridates to date. Combined experimental and theoretical investigations indicate that the exceptional anisotropy and coercivity originate from the synergistic effect between strong lattice frustration in the coupled 3d-5d honeycomb lattice network and the robust spin-orbit coupling of the Ir4+ (Jeff = 1/2) state. This work positions NiIrO3 as a promising platform to investigate low-dimensional and frustrated quantum spin systems, and highlights its potential for spintronic applications through the targeted engineering of 3d-5d interactions.

Kagome materials with charge density waves (CDWs) are fascinating quantum systems, offering an ideal platform to explore intertwined orders and to uncover novel mechanisms behind CDW formation. Chemical models have been developed and applied to predict CDW in AM6X6-type kagome materials, such as the rattling chain model based on ScV6Sn6 and the magnetic energy-saving model based on FeGe. In this study, we successfully synthesized Ti0.85Fe6Ge6 single crystals using the vapor transport method. As predicted by the rattling chain model, these crystals are expected to exhibit kagome CDW behavior. Magnetization measurements indicate that Ti0.85Fe6Ge6 is an easy-axis antiferromagnet with TN = 488 K, and transport measurements reveal metallic behavior primarily driven by electron-type carriers. However, no clear signatures of a CDW were observed in Ti0.85Fe6Ge6. Density functional theory calculations demonstrate a markedly distinct electronic structure compared to related compounds: instead of a carrier-doping-induced rigid shift, the density of states shifted away from the Fermi level. Consistent with our structural investigations, the absence of a CDW and the unusual band structure can be attributed to the bonding characteristic within Ti0.85Fe6Ge6. The strong covalent bonds of Ti-Ge1b, along with the solid Ge1b-Ge1b dimers, prevent the Ti-Ge1b-Ge1b-Ti chain from rattling. The presence of an Fe-Fe antibonding state at the Fermi level enhances the spin polarization and depletes the electronic density around the Fermi level. Our results suggest that both the ionic radius and the bonding characteristics of the filler atom are crucial for the formation of CDWs in kagome materials. These factors can serve as supplementary terms to the rattling chain model, providing new insights for the discovery of novel kagome CDW materials.

In a magnetic skyrmion phase, magnetic moments form vortex-like topological textures which are of both fundamental and industrial interests. In $\beta$-Mn-type Co-Zn-Mn alloys, chrial magnetic skyrmions emerge above room temperature, providing a unique system for studying the skrymion physics and exploring spintronics applications. However, the magnetic skyrmion phase is typically confined in a narrow and limited temperature ($T$) and magnetic field ($H$) range. Here, we demonstrate that hydrostatic pressure can expand the skyrmion phase in the $T-H$ phase diagram of single-crystalline Co$_8$Zn$_8$Mn$_4$. At ambient pressure, signatures of skyrmions are seen within $T\sim302-308$ K and $H\sim50-100$ Oe. Applying a moderate pressure of 6 kbar extends this range to $T\sim300-310$ K and $H\sim50-150$ Oe. However, further escalation of pressure to 10 kbar results in a slight contraction of the skyrmion phase. These findings underscore the sensitivity of the skyrmion phase in Co$_8$Zn$_8$Mn$_4$ to external pressures, and hint at the potential of strain engineering, particularly in $\beta$-Mn-type Co-Zn-Mn thin films, as a promising avenue to customize the skyrmion phase.

We report a dynamic magnetostrictive effect in type-II superconductors (e.g., Nb, YBa2Cu3O7-x, Bi2Sr2CaCu2O8+delta and Ba0.6K0.4Fe2As2) and any type-II superconductor is expected to present a similar response to this new technique. Measured via a composite magnetoelectric technique, an ac field excites an in-phase, nondissipative strain response scaling linearly with vortex density in the vortex lattice phase. In the vortex liquid phase, the signal acquires an out-of-phase component before vanishing in the normal state. We propose the ac strain susceptibility a thermodynamic criterion for the vortex lattice, capturing vortex collective modes inaccessible from static measurements.

Electric-field (E) modulation of magnetic order in hybrid materials remains of significant interest for multiferroic metal-organic frameworks. Here, we investigated the spin-resonance response of single-crystal [(CH3)2NH2]Fe(HCOO)3 (Fe-MOF) via X-band electron spin resonance (ESR) under four cooling conditions, including zero-field cooling (ZFC), magnetic-field cooling (HFC), electric-field cooling (EFC), and combined electric- and magnetic-field cooling (EHFC). These measurements revealed protocol-dependent variations in the resonance field (Hr) and double-integral intensity (I) within the magnetically ordered phase below ∼18.5 K (TN). After EFC, E variation from 0 to 2.2 MV/m and back produced small but reproducible Hr shifts (ΔHr ≈ 0.3 mT) and systematic I(E) variations. While under EHFC, E variation from +2.2 to -2.2 MV/m and back produced a larger symmetric modulation (ΔHr ≈ 1.2 mT) and reversible I(E) changes. The electric-field response decreased progressively with increasing temperature, and it became negligible at TN, indicating that the effect was confined to the magnetically ordered phase. These results demonstrated electric-field sensitivity of the resonance response, consistent with dipole-coupled spin interactions in the framework.

The Berry phase accumulated along a cyclotron orbit encodes important information about electronic band topology and is commonly inferred from the phase of quantum oscillations. Measurements of the ac magnetostrictive coefficient have recently emerged as a sensitive thermodynamic probe of quantum oscillations, but the phase offset has not been experimentally calibrated. Here, using the topological antiferromagnet YbMnBi_2, we calibrate this offset by directly comparing quantum oscillations in magnetization with those in the ac magnetostrictive coefficient. Measurements of both responses on the same single crystal reveal a single fundamental frequency of approximately 160 T in fields up to 14 T, enabling a direct phase comparison free from ambiguities associated with multiple frequencies. We observe an approximately π/2 relative phase shift between the two oscillatory responses, consistent with the Maxwell relation linking the magnetostrictive coefficient to the stress derivative of magnetization. Our results establish the appropriate phase needed to extract cyclotron-orbit phase information from quantum oscillations in the ac magnetostrictive coefficient.

Spin-split electronic structures in compensated antiferromagnets are commonly sought in the nonrelativistic limit, where magnetic order lifts spin degeneracy without spin-orbit coupling (SOC). Whether SOC can instead be the indispensable symmetry-breaking ingredient remains largely unexplored. Here we combine quantum oscillations detected by ultrahigh-sensitivity ac magnetostriction, magnetic-symmetry analysis and first-principles calculations to resolve the bulk Fermi-surface evolution of SmBi across two successive antiferromagnetic (AFM) transitions. New oscillation branches emerge below TN and undergo a further reconstruction below T*, whereas isostructural SmSb shows no comparable change. For the candidate noncollinear orders of SmBi, breaking global parity-time symmetry is insufficient in the nonrelativistic limit because residual spin-space symmetries protect twofold band degeneracy; conversely, SOC alone cannot lift the degeneracy of the centrosymmetric paramagnetic (PM) phase. Only the coexistence of noncollinear order and SOC locks spin to the lattice and removes the residual protection. SmBi therefore realizes a cooperative, relativistic route to spin-split Fermi surfaces, broadening unconventional magnetism beyond systems whose splitting is already present in the nonrelativistic limit.

Geometrically frustrated magnets provide an ideal platform for exploring the interplay between lattice geometry and spin degrees of freedom. Here, we investigate the interactions between lattice and spin via thermal-transport measurements on the triangular sawtooth-lattice olivine magnet Fe2SiSe4, which exhibits successive magnetic transitions at T1 = 110 K (antiferromagnetic) and T2 = 50 K (ferrimagnetic). Although phonons dominate the thermal conductivity, its temperature dependence displays a pronounced double-peak structure arising from spin-phonon coupling. In the intermediate temperature range between T1 and T2, resonant scattering of phonons by magnetic excitations around 5 meV produces abroad maximum around 60 K. Below T2, the resonant spin-phonon scattering is strongly suppressed, leading to a rapid increase in thermal conductivity upon cooling and a pronounced low-temperature peak near 11 K, characteristic of heat transport governed by conventional phonon scattering mechanisms. Notably, this low-temperature peak is enhanced by a factor of similar to 5 compared to the broad maximum at higher temperatures. These results demonstrate the strong sensitivity of thermal transport to spin-lattice interactions and highlight spin-phonon scattering as an effective mechanism for tailoring thermal conductivity in geometrically frustrated magnets.

The rational design of new materials emerges as an important direction to explore new topological materials, which is based on the understanding of the correlation between crystal and electronic structures. In this paper, we perform a comprehensive study on the crystal and electronic structures in LaAgAs2 through a combination of single-crystal x-ray diffraction (XRD), quantum oscillation, and angle-resolved photoemission spectroscopy (ARPES) experimental measurements, and density functional theory (DFT) calculations. Single-crystal XRD measurements reveal that LaAgAs2 crystallizes into a HfCuSi2-derived structure with the square net distorted into cis-trans chains. Quantum oscillation measurements reveal two frequencies with small effective masses and quasi-two-dimensional (2D) characters. ARPES measurements reveal an electronic structure strikingly different from the square-net-based semimetals, such as LaAgSb2. The Fermi surface is quasi-two-dimensional (2D), with Dirac-like hole pockets at the zone center and a quasi-1D elliptical electron pocket at the zone boundary. Based on the DFT calculations, the measured electronic structure can be well understood regarding the cis-trans distortion, which transforms the two-dimensional square net-derived Dirac bands into quasi-1D trivial bands. Intriguingly, multiple topological states can be identified around the zone center, including a nontrivial Z2 topological surface state and a bulk Dirac state. Our study clarifies the impact of cis-trans distortion and identifies LaAgAs2 as a topological material with multiple topological states near the Fermi level, providing a guideline for intentionally designing new topological materials.

The Fermi surface structure in the half-Heusler semimetallic compound LuAuSn was systematically investigated using quantum oscillation studies of high-quality single crystals and first-principles calculations. Clear bulk quantum oscillation signals were observed for multiple complementary physical properties, including magnetization, Hall resistance, and dynamic magnetostrictive coefficient. Quantum oscillations measured in a strong magnetic field (up to 35 T) confirmed the existence of four hole pockets and two electron pockets. Furthermore, spin splitting caused by spin-orbit coupling was discovered in the hole pockets. Our findings revealed the detailed topology of the Fermi surface in LuAuSn, which may help improve understanding of the electronic transport in this and related half-Heusler materials. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic); (sic)(sic)(sic)(sic)(sic)(sic)(sic)Berry(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Half-Heusler(sic)(sic)LuAuSn(sic)(sic),(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)LuAuSn(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic):(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic); (sic)(sic)(sic)(sic)Berry(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Half-Heusler(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

We investigate flux dynamics in the high-entropy alloy superconductor (TaNb)(0.7)(HfZrTi)(0.5) after annealing (as-cast, 500, 550, and 1000 degrees C) using a sensitive ac composite magnetoelectric method that measures the complex ac magnetostrictive coefficient (d lambda/dH)(ac). The resulting vortex phase diagrams show that intermediate annealing (about 500-550 degrees C) induces nanoscale clustering, enhances pinning, and produces a pronounced fishtail effect with successive elastic- and plastic vortex-glass regimes. Flux-jump instabilities are observed at an annealing temperature of 550 degrees C and persist at 1000 degrees C, indicating strong pinning and thermomagnetic instability in the low-temperature, low-field regime. Remarkably, the 1000 degrees C sample exhibits a two-step superconducting response-a double plateau or drop in d lambda '/dH and two dissipation peaks in d lambda ''/dH-demonstrating the coexistence of two superconducting phases with distinct irreversibility and critical-field value. We further show that the resolvability of the two-step (d lambda/dH)(ac) signature is governed by the topological connectivity of the phase-separated microstructure, which controls magnetic shielding between the TaNb-rich network and the (TaNb)(0.7)(HfZrTi)(0.5) parent phase. These results establish a direct microstructure-vortex-state correlation and provide a route to tailoring flux pinning in chemically complex superconductors via thermal processing.

In thermodynamics, volume is an essential extensive variable. Strain-line, area, or volume change-therefore offers a direct window into correlated quantum matter: tiny length changes ΔL track how the lattice responds when state variables such as magnetic field H and/or temperature T are varied, revealing phases, transitions, and dynamics. Direct, high-precision strain measurements are already difficult; their susceptibilities are harder still. Very recently, several direct techniques have made vital progress on two key quantities: the magnetostrictive coefficient dλ/dH (often denoted qijk or dij in the magnetostriction literatures), and the linear thermal-expansion coefficient α= dλ/dT. Considering these two strain susceptibilities together-they are fundamental and complementary-clarifies why these thermodynamic properties merit renewed attention.

In the ferrimagnetic semiconductor Mn3Si2Te6, a colossal magnetoresistance (CMR) is observed only when a magnetic field is applied along the magnetic hard axis (H c). This phenomenon suggests an unconventional CMR mechanism potentially driven by the interplay between magnetism, topological band structure, and/or chiral orbital currents (COC). By comparing electrical resistance measurements using continuous direct currents and pulse currents, we found that the current-induced insulator-metal transition, supporting the COC-driven CMR mechanism, is likely a consequence of Joule heating effects. First-principles calculations reveal a pronounced band-gap reduction upon tilting the magnetic moments toward the c axis, accompanied by increased carrier concentration and Fermi velocity. Combining spin-orientation-dependent electronic structure with Boltzmann transport theory, the calculated electrical resistance closely reproduces the CMR observed experimentally. These findings suggest that the CMR in Mn3Si2Te6 stems primarily from band-gap reduction induced by partial polarization of magnetic moments along the magnetic hard axis.

In correlated quantum materials, divergent critical fluctuations near the quantum critical point are often closely associated with exotic quantum phases of matter, such as unconventional superconductivity and quantum spin liquids. Here we present a simple yet highly sensitive composite magnetoelectric (ME) method for detecting the critical spin fluctuations in quantum magnets. The ME signal is proportional to the magnetostriction coefficient, which directly probes the product of magnetization and spin-spin correlation. As a demonstration, the composite ME method is applied to a Kitaev quantum spin liquid candidate Na3Co2SbO6, which shows signs of magnetic field-induced quantum criticality. Notably, the ME signal prominently diverges at the magnetic field-induced tricritical points, particularly at a tricritical point that lies in close proximity to a zero-temperature quantum critical point. A crucial aspect of these tricritical points is their tunability through the modification of the in- plane magnetic field's direction. The direction of magnetic field can thus serve as a handy yet important tuning parameter, alongside pressure and chemical doping, for searching quantum critical points in quantum magnets with pronounced magnetic anisotropy.

Two-dimensional (2D) magnetic materials have attracted considerable interest owing to their potential applications in spintronics and fundamental investigations into low-dimensional magnetism. Cr2Te3, a quasi 2D non van der Waals magnet, exhibits a complex magnetic phase diagram due to competing magnetic interactions within and between layers. However, the precise nature and evolution of these magnetic phases remain unclear. Here, we utilize an ultrahigh-sensitive composite magnetoelectric technique, which probes the ac magnetostrictive coefficient, to systematically explore the temperature magnetic field phase diagram of Cr2Te3 single crystals. Our results reveal the coexistence of multiple magnetic phases, including canted ferromagnetic, antiferromagnetic, and paramagnetic states. Another canted ferromagnetic phase and a possible triple point have been proposed. The updated phase diagram provides deeper insights into the specific spin configurations associated with each phase. These findings also highlight the decoupled magnetic ordering between the Cr1/Cr3 layers and the Cr2 layer near the magnetic ordering temperature.