Newsfeeds

Journal of Physics: Condensed Matter - latest papers

Latest articles for Journal of Physics: Condensed Matter

IOPscience

  • The spin-S Heisenberg antiferromagnet on the Shastry–Sutherland lattice
    Recent advances in the orthogonal-dimer spin- Heisenberg antiferromagnet are reviewed. This model has been examined for more than 40 years since it was originally studied by Shastry and Sutherland. The discovery of SrCu (BO ) as a good candidate material for the system led to a considerable advancement in subsequent research. In the case when is larger than 1/2, however, the elucidation of the properties of the system was relatively delayed. In the ground state of general- systems, interesting quantum phase transitions occur not only for . In this article, the systematic behavior depending on which has been recently clarified by unbiased and numerical computational calculations is reviewed. The effects due to spin anisotropy as determined from experimental and theoretical results are also overviewed. We also mention recent developments for the system.

  • Electronic and thermal transport properties of two-dimensional penta-Pd 2 ...
    Two-dimensional thermoelectric materials have gained considerable attention because of their potential for high energy-conversion efficiency and miniaturized device applications. In this work, the structural, thermal stability, and thermoelectric properties of a novel pentagonal Pd As monolayer are investigated using density functional theory. The optimized structure is found to be thermally stable and exhibits a direct band gap of 0.80 eV located in the infrared region. The lattice thermal conductivity ( ) is calculated to be 2.26 W (mK) at room temperature 300 K and decreases to 1.0 W (mK) at high temperature 700 K, indicating strong phonon scattering. Carrier relaxation times are estimated using the deformation potential theory of Bardeen and Shockley and subsequently employed within the Boltzmann transport framework to evaluate thermoelectric coefficients. A bipolar effect is identified at elevated temperatures due to the relatively small band gap. The combination of high power factor and low lattice thermal conductivity results in an enhanced thermoelectric figure of merit, with a maximum of 3.0 for n-type doping and 1.2 for p-type doping. These findings demonstrate that penta-Pd As is a promising candidate for high-performance thermoelectric applications. Furthermore, the potential applicability of the investigated material for future thermophotovoltaic devices is also discussed.

  • Orbital matching governs perturbation-driven charge transmission in amorphous IGZO
    Amorphous indium–gallium–zinc oxide (IGZO) exhibits substantially faster charge transport than its constituent single oxides, yet the microscopic origin of this multiplication advantage remains unclear. To investigate the microscopic origin of this behavior, we employ dynamic ozone perturbation as a probe of charge propagation in IGZO and compare its response with those of ZnO and In2O3. While the single-oxide systems display pronounced slow relaxation components associated with delayed transport from the surface into the bulk, IGZO exhibits a strongly suppressed slow process, yielding transients that are effectively described by a single characteristic timescale. Raman and photoluminescence spectroscopy reveal defect-related sub-gap states associated with ZnO4 structural motifs, suggesting that local structural disorder plays an active role in electronic transport. Besides oxygen-vacancy-related states, the Raman 2LO mode directly points to the involvement of ZnO4-associated defect structures. Rather than representing isolated point defects, these motifs may indicate local coordination distortions that alter the connectivity between neighboring cation environments. Density-functional calculations further show that ozone preferentially adsorbs on In sites, producing localized surface polarization. Partial charge analysis and Wannier-based electronic reconstruction identify an In–O–ZN transport pathway in which orbital-matched ZN–O bridges efficiently relay the surface perturbation into the amorphous network. This identified transport pathway is absent in the corresponding single oxides and provides a direct electronic connection between surface-localized charge accumulation and bulk transport. These results suggest that the enhanced performance of amorphous multiplication oxides extends beyond conventional concepts of band alignment, carrier modulation, and defect engineering. Instead, orbital compatibility between dissimilar cation environments may create emergent transport pathways that qualitatively alter charge propagation. Our findings introduce orbital connectivity as a complementary descriptor for understanding transport in complex amorphous oxide semiconductors.

  • Pressure induced electronic and structural transition in Ba 2 ...
    This study explores the pressure evolution of the double perovskite Ba NiTeO by employing experimental and computational techniques. For the study of structural and vibrational properties, synchrotron x-ray diffraction and micro-Raman spectroscopic experiments at high-pressures were carried out. As a complementary study, DFT simulations of the structural properties as a function of pressure were performed to support and explain the experimental findings. Furthermore, the electronic and magnetic properties as a function of pressure were investigated using DFT. Our study reveals a structural phase transition from a rhombohedral to a monoclinic phase at high pressure, accompanied by a significant increase in bulk modulus. Raman anomalies near 1 GPa coincide with a calculated direct-to-indirect band-gap crossover, suggesting a possible electronic contribution to the vibrational response. A minimum in the Raman mode full-width-half-maximum (FWHM) at about 11 GPa, coincides with a local structural reorganization in the sample, indicated by a drop in the distortion index of NiO octahedra as well as a discontinuity in the ratio.

  • Ultralow-temperature spin kinetics of strongly hybridized electro-nuclear excitations in LiHoF 4 ...
    Recent cavity-magnon-polariton spectroscopy of the quantum Ising magnet LiHoF represents a remarkable experimental achievement, providing high-fidelity baseline spectra of electro-nuclear spin transitions. However, the interpretation of these results using a standard single-ion mean-field theory predictably falls short in describing many-body dynamic correlations, leaving several pronounced anomalies unexplained: double peaks of dissipation near the quantum critical point, bell-shaped transition linewidths, and the collectivization of discrete transitions below the critical field. In this paper, we formulate a theoretical framework based on the low-temperature spin kinetics framework. By incorporating a chemical potential for electro-nuclear excitations ( ) and deriving the dynamic susceptibility via the non-equilibrium statistical operator method, we provide a unified analytical resolution for these anomalies, offering a complete thermodynamic description of the strongly hybridized spin dynamics.