physica status solidi (b) Basic Solid State Physics

Mamun‐Or‐Rashid, Md.; Yagi, Shuhei; Yaguchi, Hiroyuki

doi: 10.1002/pssb.70219pmid: N/A

The structural properties of ion‐implanted GaP:N are investigated using high‐resolution X‐ray diffraction as a function of nitrogen concentration and post‐implantation annealing. The nitrogen‐ion‐implanted samples exhibit lattice expansion with N composition due to the formation of N‐related complexes, mainly N–P split interstitials. This contrasts with the lattice contraction typically observed in epitaxially grown dilute nitride semiconductors. Post‐implantation annealing reduces the lattice expansion by releasing P from the N–P split interstitials and transforming them into NP substitutionals. These findings highlight the potential of ion implantation as an effective approach for realizing dilute nitride semiconductor‐based devices with improved lattice matching to the substrate.

Cheng, Shu‐liang; Meng, Yue; Zhang, Liu‐chang; Zhang, Shuo; Xin, Ya‐jun; Sun, Yong‐tao; Wang, Yang; Zhao, Qing‐xin

doi: 10.1002/pssb.202500460pmid: N/A

Based on the principles of localized resonance and finite element analysis, this paper proposes several novel acoustic metamaterial thin plates. These structures undergo numerical analysis and optimization, with the optimized configuration achieving a minimum onset frequency of 143.2 Hz, thereby fulfilling the objective of low‐frequency vibration damping and noise reduction. By analyzing the mode shapes of the structure at different frequencies, the opening mechanism of the low‐frequency bandgap is revealed. This phenomenon primarily results from rotational resonance of the scatterers, coupled with displacement resonance and localized resonance of the elastic plate. The accuracy of the bandgap of the structure can be proven by performing a transfer characterization of the structure, which shows a minimum transmission coefficient of −177.5, corresponding to a frequency of 322 Hz. Subsequently, analyzing the displacement contour plots of the structure under different excitation frequencies provides a clear visual representation of the variations in the structure's ability to suppress elastic wave propagation. Observations from group velocity and phase velocity images reveal that frequency variations exert a significant influence on the propagation direction, propagation velocity, and energy transfer of elastic waves within the structure. The thin‐plate structure proposed in this paper holds significant practical application potential for suppressing low‐frequency noise and vibration in real‐world engineering scenarios.

Mistri, Hiranmay; Ghosh, Anumoy; Sardar, Abdur Rahaman

doi: 10.1002/pssb.70196pmid: N/A

In this article, a dual‐channel, metasurface‐based frequency‐multiplexed binary amplitude shift keying (ASK) modulator is developed for terahertz applications. The metasurface building block is designed on a gold‐backed, reflective silicon dioxide (SiO2) substrate and consists of one hexagonal and one elliptical graphene monolayer patch. The device operates as a dual‐channel binary‐ASK modulator with two distinct channels at 1.45189 and 1.79571 THz. Both channels exhibit high extinction ratios of at least 17.05 and 10.20 dB, respectively. The device offers excellent modulation depth of at least 83.88% (maximum 98.02%) and 89.76% (maximum 90.45%), and exceptionally low insertion loss with maximum values of 0.757 and 0.282 dB, respectively. The proposed binary‐ASK scheme provides an extremely low bit‐error rate, which is very close to zero for both coherent and noncoherent detection. By leveraging the tunability of graphene, digital data bits are encoded through variation of the chemical potential (CP). A CP value of 0 eV represents the input data bit ‘0’, while a CP value of 1.0 eV represents the input data bit ‘1’. The device demonstrates ultimate suitability for ultra‐high‐speed wireless communication in beyond‐5G and 6G networks, secure wireless links for defense applications, terahertz imaging, and spectroscopic sensing systems.

Votyakov, Sergei A.; Osadchy, Alexander V.; Obraztsova, Elena D.

doi: 10.1002/pssb.202500343pmid: N/A

Ultra‐narrow graphene nanoribbons (GNRs) demonstrate bright photoluminescence (PL) with parameters determined by GNR geometry. Combination of wide variable spectrum and fast electronic relaxation permits to consider GNRs as a potential active laser material. To avoid reabsorption of light and to realize laser generation, it is necessary to use nonstandard resonators. This study theoretically investigates microspherical resonators supporting whispering gallery modes for lasing in the visible/near‐infrared range, focusing on optimizing the design for efficient light amplification. The selected spectral range is well suited for GNRs, which offer a compelling alternative to traditional gain materials as a result of their tunable electronic properties and high PL intensity. The maximization of the Q‐factor, essential for lasing, is limited by parasitic modes with higher radial numbers. Specifically, for a commonly used 6 µm diameter polystyrene microsphere (refractive index N = 1.57) in air, modes with radial numbers n = 1, n = 2, and n = 3 coexist within the spectral range of 550–850 nm, with a mode spacing of less than 1 nm. This results in groups of closely spaced modes (n = 1, n = 2, and n = 3) appearing throughout the resonant spectrum, with the lowest Q mode (n = 3) dictating the overall performance of each group. We explored strategies to suppress parasitic modes, including reducing the diameter of the microsphere and modifying the refractive index of the surrounding medium. Single‐mode operation (n = 1) within the selected spectral range is achievable, but at the cost of reducing the Q‐factor of the fundamental mode (the highest Q mode, absent parasitic modes) to approximately 103$^3$ which can be achieved by selecting a polystyrene microsphere with a diameter of approximately 2.8 µm. Interestingly, operating with two modes (n = 1 and n = 2) can offer a compromise, as the n = 2 mode can exhibit a Q‐factor comparable to the fundamental mode in the absence of higher‐order modes, potentially reaching Q near 103$^3$. Operation with two modes (n = 1 and n = 2) is achievable by choosing a larger diameter microsphere, approximately 4.8 µm. Parasite modes limit achievable Q. Suppressing them via microsphere diameter reduction presents a practical route toward creating functional microresonator devices.

Moqine, Younes; Adnane, Brahim; Khribach, Aziz; El Houri, Abdelghani; El Mouatasim, Ayyoub; Houça, Rachid

doi: 10.1002/pssb.202500489pmid: N/A

In this article, we investigate how various parameters such as the nanoribbon length, temperature, external magnetic field, and Coulomb interactions affect fundamental quantum correlations in zigzag graphene nanoribbons. Using an effective Heisenberg model derived from the Hubbard Hamiltonian, we analyze three essential quantifiers: thermal entanglement, correlated quantum coherence, and local quantum uncertainty. Our results reveal that increasing the ribbon length leads to an exponential reduction of the exchange interaction between edge‐localized electronic states, which causes a gradual decrease of thermal entanglement. Both temperature and Coulomb repulsion significantly reduce the concurrence, while quantum coherence and local quantum uncertainty exhibit greater robustness, maintaining nonclassical correlations even at elevated temperatures. Furthermore, the application of an external magnetic field strongly influences these quantum correlations and enhances their sensitivity to thermal and geometric effects. These findings provide a comprehensive understanding of how structural and environmental parameters govern quantum correlations in graphene‐based nanostructures, offering valuable insights for the design of stable platforms for quantum information processing and spintronic applications.

Zhao, Chuan‐Zhen; Li, Hui

doi: 10.1002/pssb.70214pmid: N/A

The electronic and optical properties of CuGaxIn1−xSe2 are explored in the full component range through first‐principles calculations. Our findings demonstrate that the lattice parameters decrease as the Ga component increases. CuGaxIn1−xSe2 is an alloy with a direct bandgap. Its bandgap enlargement is due to the rise of the conduction band minimum (CBM) and the fall of the valence band maximum (VBM). Our findings also show that Cu plays a secondary role in determining the dependence of the VBM on Ga component because the Cu‐3d and Cu‐4p states are nearly independent of the Ga component. The rise of the CBM is caused by the enhanced total sIII−cation−sVI−anion$\begin{equation*} s_{III-\textit{cation}}-s_{VI-\textit{anion}} \end{equation*}$ coupling, while the fall of the VBM is mainly due to the enhanced total pIII−cation−pVI−anion$\begin{equation*} p_{III-\textit{cation}}-p_{VI-\textit{anion}} \end{equation*}$ coupling. Analysis of the imaginary part of the dielectric function reveals that the transition energies of the critical points E0, E1(A), E1(B), E2(A), E2(B), and E3 move toward the higher‐energy direction approximately linearly in the whole component range. Similar results are also found by analyzing the absorption spectra, refractive index spectra, and reflectivity spectra.

Ramakrishna, B.; Charan, P. H. K.; Jagadeesh, Ch.; Patnaik, P. Suresh; Gouthamsri, S.; Ramanaiah, M.

doi: 10.1002/pssb.70218pmid: N/A

Here we reporting the structural, optical, magnetic and dielectric properties of PrFeO3 (PFO) and Pr0.925Ce0.025Nd0.025Sm0.025Fe0.95Ti0.025Mn0.025O3 (PCNSFTMO) nanomaterials, which were prepared via sol–gel method. The synthesized nanomaterials exhibited a single‐phase with a crystal structure of an orthorhombic phase with space group Pbnm, which was confirmed through powder X‐ray diffraction (XRD) studies. Rietveld refinement was further confirmed for the formation of single phase without any detectable impurities in the synthesized nanomaterials. Transmission electron microscopy (TEM) images show that the average particle size was 56 nm for PFO and 41 nm for PCNSFTMO. The higher optical bandgap of PCNSFTMO nanomaterials when compared to PFO nanomaterial was explained through the electronegative difference between the O (oxygen) and the metal atom at the B‐site. The calculated saturation magnetization (Ms) values for PCNSFTMO were 3.91 emu/g, which is nearly double that of PFO nanomaterials. The dielectric constant and dielectric loss of PCNSFTMO and PFO at different temperatures was also studied. These results clearly indicating that the PCNSFTMO nanomaterials could be a better candidate than that of PFO nanomaterials for usage of different applications.

Boutaiba, Farouk; Aidouni, Ahmed Amine; Ould‐Mohamed, Mounir; Belkharroubi, Fadila

doi: 10.1002/pssb.202500624pmid: N/A

We present a first‐principles study of the structural, mechanical, electronic, and thermoelectric properties of three previously unexplored half‐Heusler compounds: NbOsBi, TaOsBi, and VOsBi. The nonmagnetic γ$\gamma$‐phase is found to be the most stable configuration for all three systems. Mechanical stability of the cubic C1b$C1_b$ structure is confirmed via Born–Huang criteria and phonon analysis. Electronic structure calculations show that NbOsBi and VOsBi are indirect semiconductors with HSE06+SOC band gaps of 1.09 and 0.95 eV, respectively, whereas TaOsBi exhibits metallic behavior at the Perdew–Burke–Ernzerhof level and semimetallic character under HSE06+SOC. Thermoelectric analysis indicates that NbOsBi and VOsBi achieve high Seebeck coefficients and low lattice thermal conductivity, resulting in figures of merit (ZT$ZT$) of up to 0.742 and 0.730 at 900 K, respectively. These results suggest that these materials may act as potential candidates for thermoelectric applications.

Wang, Yingyu; Wan, Rundong; Yang, Jiakang; Zhu, Kaihua; Wang, Shuaikang; Mao, Dandan; Tian, Guocai; Zhang, Zhengfu; Li, Mengnie

doi: 10.1002/pssb.70220pmid: N/A

Suppressing lattice thermal conductivity is essential for high‐performance thermoelectric materials. Here, first‐principles calculations combined with the linearized Boltzmann transport equation and deformation potential theory were used to investigate the thermal transport and thermoelectric behavior of X2Se2S (X = Bi, As, and Sb). A counterintuitive mass‐dependent trend was identified: despite being the lightest compound, As2Se2S exhibits the lowest lattice thermal conductivity, reaching 0.443 W m−1 K−1 at 300 K. This behavior can be understood within the complete Slack framework, in which lattice anharmonicity dominates over atomic mass in determining heat transport. Phonon dispersion and anharmonic force‐constant analyses show that strong acoustic‐optical coupling and abundant low‐frequency optical modes in As2Se2S enhance phonon scattering, whereas Bi2Se2S retains a clear acoustic‐optical gap and correspondingly higher thermal conductivity. Owing to its ductile mechanical response and favorable electronic structure, p‐type As2Se2S achieves a maximum ZT of 0.503 at 850 K, while Sb2Se2S shows promise for n‐type transport. These results clarify the role of anharmonicity in X2Se2S compounds and highlight their potential for low‐cost medium‐temperature thermoelectric applications.

Maddileti, Sathani; Mukherjee, Supratik; Muñoz, Alfonso; Vaitheeswaran, G.

doi: 10.1002/pssb.202500274pmid: N/A

This present study offers a comprehensive understanding of the structural, vibrational, elastic, electronic, and optical properties of zinc‐based ternary oxides Zn3X2O8 (X = P, V) using density functional theory (DFT) calculations. Zn3P2O8 and Zn3V2O8 crystallize in monoclinic and orthorhombic structures, respectively. The phonon density of states indicates that oxygen, along with both cations (Zn, X), actively participate in the low‐frequency vibrational modes. Conversely, X and O atoms primarily contribute to the higher and mid‐phonon frequencies. A blue shift in the computed frequencies was observed upon transitioning from X = P → V atom. The dynamical and mechanical stability of Zn3X2O8 was established through the evaluation of phonon dispersion relations and elastic constants. The Elastic constants and the Bulk modulus (B) suggest that Zn3P2O8 (B = 89.77 GPa) is more compressible than Zn3V2O8 (B = 130.21 GPa) and both compounds exhibit sensitivity to shear forces. Poisson's and Pugh's ratios confirm the predominant ionic bonding and ductile nature of these compounds. The electronic band structure, calculated using the HSE06 hybrid functional for improved accuracy, shows that the conduction band minima are primarily composed of Zn‐s states, with a smaller contribution from p states. Meanwhile, the valence band maxima are predominantly derived from oxygen p states, which play a key role in the electronic transitions. Calculated electronic and optical properties suggest that the studied compounds may be suitable for photoluminescence applications.