Physica Status Solidi B: Basic Solid State Physics

Viglione, Rosario G.; Castorina, Giovanni; Calogero, Gaetano; Fisicaro, Giuseppe; Ricciarelli, Damiano; Deretzis, Ioannis; La Magna, Antonino

doi: 10.1002/pssb.202500612pmid: N/A

Neutral silicon‐carbon divacancies (VSiVC0$\mathrm V_{\mathrm C}^0$) in cubic silicon carbide (3C‐SiC) are promising point defects for quantum technologies based on active crystalline centers. Within the theoretical framework of spin‐polarized density functional theory, this study examines the structural and electronic characteristics of VSiVC0$\mathrm V_{\mathrm C}^0$ centers near a hydrogen‐terminated 3C‐SiC(001) surface. A (2 × 1): H reconstructed slab of 628 atoms represents the near‐surface environment, with divacancies located at depths ranging from 0.6 to 1.2 nm in basal and axial orientations. The optimized geometries show localized relaxations, and the electronic structure reveals in‐gap defect levels in both spin channels. Furthermore, examination of the zero‐field splitting tensor demonstrates sensitivity to the orientation of the spin defects and their distance from the surface. The findings of this investigation suggest that surface proximity exerts a substantial influence on the spin Hamiltonian of divacancies, providing insight for the engineering of SiC‐based qubits and nanoscale quantum devices.

Imran, Ayesha; Choubani, Karim; Saeed, Namal; Fatima, Humawa; Almeshaal, Mohammed A.; Fatima, Fareeha; Rasul, Muhammad Nasir

doi: 10.1002/pssb.202500503pmid: N/A

First‐principles computations have been performed to examine the physical attributes of CoAsX (X = Ti, Zr, Hf) ternary compounds. The calculations have been conducted using density functional theory‐based WIEN2K package. To better corroborate the outcomes, the generalized gradient approximation of Perdew–Burke–Ernzerhof and the modified Becke–Johnson of Tran Blaha have been employed. Titled compounds exhibit the structural, dynamical, and mechanical stability with optimized lattice constants 5.988 Å, 6.260 Å, and 5.789 Å. The calculated formation energies support the experimental synthesis of these compounds. The electronic properties, including the band structure and density of states, indicate the semiconducting nature of CoAsX (X = Ti, Zr, Hf) compounds. Furthermore, the optical attributes unveil that the compounds have comparatively low reflectivity and good absorbance in the visible to UV range. These unique characteristics render them suitable for coatings with antireflective properties on optical equipment along with solar panels for enhancing light absorption. The crystal orbital Hamilton population analysis revealed the strongest bonding in X–Co coupling. The CoAsX compounds have a lot of intriguing possibilities in optoelectronics including photodetectors, photovoltaics, and as automotive photoswitches.

Mishra, Kulbhushan; Joshi, Rajeev; Rawat, Rajeev; Bhobe, Preeti A.

doi: 10.1002/pssb.202500443pmid: N/A

Heusler alloys are typically metallic, with high electrical conductivity and a positive temperature coefficient of resistivity. Finding semiconductor‐like behavior, where resistivity increases with decreasing temperature, suggests unexpected changes in the scattering mechanisms of the charge carriers. Herein, the temperature‐dependent behavior of electrical resistivity, ρ(T), of Fe2Ti0.5Mn0.5 Sn is investigated. The ρ versus T plot is semiconductor‐like, showing a quasilinear behavior over an extended temperature region. This unusual behavior of ρ(T) can be described within the Cote–Meisel formalism based on the diffraction model of strongly disordered metals. Further, below 30 K the electrical resistivity obeys a T1/2 law, which is explained by the weak localization effect. The negative magnetoresistance supports the weak localization scenario. X‐ray diffraction and magnetization measurements also confirm the presence of strong disorder, strain‐induced tetragonal distortion, and a small fraction of the secondary hexagonal Fe2MnSn phase in the prepared composition. Together, these features provide a natural explanation for the deviation of transport and magnetic properties from those predicted for the ideal ordered L21 structure. The current study discusses the systematic approach to understanding the anomalous transport property of disordered Heusler alloy.

Iwasaki, Kazuma; Abe, Seishi; Yu, Jeongsoo; Tanabe, Tadao

doi: 10.1002/pssb.202500634pmid: N/A

Magnetite (Fe3O4) possesses a 0.1 eV bandgap and exhibits responsivity to mid‐infrared radiation, making it a promising candidate to replace existing electromagnetic wave detector materials. Optimization of platinum (Pt) addition concentration to Fe3O4 thin films is expected to enhance sensitivity by facilitating the capture of electrons generated by electromagnetic radiation. In this study, to identify the optimal Pt addition concentration for enhancing the mid‐infrared detection sensitivity of Fe3O4 thin films, the response under mid‐infrared irradiation was evaluated using seven samples with Pt addition concentrations ranging from 0 at.% to 9.4 at.%. Plotting the peak intensity based on the mid‐infrared response revealed no correlation between Pt concentration and peak intensity. The sample with the highest peak intensity was the one with the highest Pt concentration in this study (9.4 at.%), exhibiting an average peak intensity of 0.014. The signal‐to‐noise (S/N) ratio, calculated based on the peak intensity of the response and the effective value of the noise, was the highest for the sample with a Pt addition concentration of 1.6 at.%, which had an electrical resistivity of 1.4 × 104 µΩ cm. This confirmed that this condition represents the optimal Pt addition amount under the conditions adjusted in this study.

Bian, Jian; Cui, Fan; Feng, Yuan; Zu, Hao; Ma, Cuiling; Shi, Wei; Lin, Haoran; Xu, Ziran; Liu, Hui

doi: 10.1002/pssb.202500480pmid: N/A

The structural and electrical characteristics of Cu‐doped LiGaCr4O8 ceramics were explored. X‐ray diffraction analysis of the samples indicated changes in the Cr−Cr bond lengths and Cr−O−Cr bond angles. The distorted CrO6 octahedra caused by doping affected the dielectric and piezoelectric properties. The dielectric properties were explored in detail, and the variations of the permittivity and loss with frequency were accurately measured from 20 Hz to 10 MHz at a range of temperatures. Cu doping enhanced the dielectric constant by approximately one order of magnitude while reducing the dielectric loss by nearly two orders of magnitude. The frequency‐dependent electrical modulus showed non‐Debye type relaxation behavior. Within the temperature measurement range, the samples exhibited both positive temperature coefficient of resistance and negative temperature coefficient of resistance characteristics. The variation in DC resistivity followed the Arrhenius equation. The activation energy of DC resistivity estimated using the Arrhenius equation exhibits a nonlinear trend. As the amount of Cu doping increased, the piezoelectric charge coefficients increased.

Liu, Shiqi; Chen, Fang

doi: 10.1002/pssb.202500601pmid: N/A

This work proposes a multimode resonant terahertz absorber consisting of two patterned graphene layers, two silicon dioxide (SiO2) dielectric layers, and a metal substrate. Simulations and analyses based on the finite element method (FEM) indicate that the absorber achieves near‐perfect absorption at 0.60, 2.42, and 4.79 THz, with corresponding absorption rates of 99.6%, 99.4%, and 99.9%, respectively. The physical mechanisms underlying the resonance peaks are elucidated through analysis of the electric field and surface current distributions at each resonant frequency. The results indicate that the resonance peak at 0.60 THz arises from an electric dipole resonance. While the 2.42 THz peak is attributed to a higher‐order quadrupolar resonance accompanied by magnetic coupling effects. The 4.79 THz resonance arises from a hybrid mode combining higher‐order quadrupolar resonance and a Fabry–Pérot (FP) cavity mode. Moreover, magnetic dipole resonance contributes to all three absorption peaks. This work is expected to significantly advance research in the field of multimode resonance. Furthermore, the absorber demonstrates polarization insensitivity and dynamic tunability, and by investigating the impact of the incident angle, it is found that even when the oblique incident angle reaches 60°, the absorption rate remains above 80%. These properties enable the absorber to play an active role in various fields, including terahertz communication technology, stealth technology, biomedical detection, and imaging, as well as security detection.

doi: 10.1002/pssb.70191pmid: N/A

Kaur, Gurdeep; Saini, Lavleen; Kaur, Sandeep; Sharma, Gopi; Singla, Shivani; Verma, Neetu

doi: 10.1002/pssb.202500636pmid: N/A

Dysprosium‐doped bismuth borosilicate glasses with and without gold nanoparticles were synthesized via the conventional melt‐quenching technique to investigate the influence of AuNP incorporation on their structural and optical properties. The amorphous nature of the as‐prepared glasses was confirmed by X‐ray diffraction (XRD), and Fourier‐transform infrared analysis revealed characteristic borate and silicate groups. The UV–vis absorption spectra demonstrated distinct surface plasmon resonance features in the AuNP‐doped sample, indicating successful nanoparticle incorporation within the glass matrix. The prepared glasses were further heat‐treated to obtain corresponding glass ceramics, and the formation of crystalline phases was verified by XRD analysis. The photoluminescence studies of glass and glass–ceramic samples showed intense emission bands corresponding to Dy3+ transitions, with a significant enhancement in luminescence intensity. The improvement is attributed to localized surface plasmon–enhanced energy transfer between Dy3+ ions and gold nanoparticles, as well as to structural ordering in the crystalline phase. These findings suggest that Dy3+‐doped bismuth borosilicate glasses and glass ceramics containing AuNPs are promising candidates for photonic and optoelectronic device applications due to their improved emission characteristics and thermal stability.

Zhang, Tongzhe; Zhu, Jun; Yi, Zao; Cheng, Shubo; Li, Boxun

doi: 10.1002/pssb.202500573pmid: N/A

This paper puts forward a novel proportional structure for a tunable broadband absorber in the terahertz (THz) frequency band, with graphene as its core material. In the pursuit of an optimal design, we maintain a proportional distance between the top graphene structure and the periodic edges. This design enables excellent absorptance, surpassing 90% in the 2.89–6.43 (3.54) THz frequency range. Notably, at f = 4.25 THz, perfect absorption is achieved. At f = 5.8 THz, the absorptance nears 95%, and at f = 5.47 THz, it is around 91%. The average absorptance within the 2.89–6.43 THz range reaches 94.5%. By calculating the impedance of the absorber, the favorable absorption frequency band is demonstrated. Moreover, analyzing the internal electric field of the absorber reveals a strong electric field coupling effect between different regions. This effect leads to the overlap of absorption peaks, thus forming a broadband response. This characteristic allows for the selection and combination of regions according to application requirements. By adjusting the absorber's parameters, it shows coordinated performance and manufacturing tolerance. Additionally, the absorber exhibits a certain tolerance to the incident angle of electromagnetic waves. These findings highlight the potential of this absorber in applications such as optoelectronic devices, THz detection, and stealth technology.

Abdesselem, Abdellatif; Siouani, Chaouki; Mahtout, Sofiane

doi: 10.1002/pssb.202500350pmid: N/A

Using first‐principles density functional theory, the impact of MnX6 (X = S, B, C, N, O) cluster doping on the structural, electronic, magnetic, and optical properties of the MoS2 monolayer is systematically investigated. The results indicate that all systems are more easily formed under Mo‐rich conditions compared to S‐rich conditions, with the MnO6‐doped system being the most energetically preferred, exhibiting a formation energy of −15.826 eV. The introduction of MnX6 clusters as dopants transforms the MoS2 monolayer into magnetic materials: MnS6 and MnO6 yield magnetic semiconductors, while MnB6, MnC6, and MnN6 produce magnetic half‐metals, making them promising candidates for spintronics applications. Furthermore, doping enhances the photoresponse by introducing a redshift in the absorption spectrum and improving absorption in both infrared and visible regions, particularly for the MnB6 and MnC6‐doped systems, making them suitable candidates for applications in infrared and visible light devices.