Journal of Physics: Condensed Matter最新文献

{"title":"Quantum geometrical properties of topological materials.","authors":"Wei Chen","doi":"10.1088/1361-648X/ad8619","DOIUrl":"10.1088/1361-648X/ad8619","url":null,"abstract":"<p><p>The momentum space of topological insulators and topological superconductors is equipped with a quantum metric defined from the overlap of neighboring valence band states or quasihole states. We investigate the quantum geometrical properties of these materials within the framework of Dirac models and differential geometry. Their momentum space is found to be always a maximally symmetric space with a constant Ricci scalar, and the vacuum Einstein equation is satisfied in 3D with a finite cosmological constant. For linear Dirac models, several geometrical properties are found to be independent of the band gap, including a peculiar straight line geodesic, constant volume of the curved momentum space, and the exponential decay form of the nonlocal topological marker, indicating the peculiar yet universal quantum geometrical properties of these models.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142406528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superconducting density of states and vortex lattice of LaRu₂P₂observed by scanning tunneling spectroscopy.","authors":"Marta Fernández-Lomana, Paula Obladen Aguilera, Beilun Wu, Edwin Herrera, Hermann Suderow, Isabel Guillamón","doi":"10.1088/1361-648X/ad82c9","DOIUrl":"10.1088/1361-648X/ad82c9","url":null,"abstract":"<p><p>We provide the superconducting density of states of the pnictide superconductor LaRu₂P₂(<i>T_c</i>= 4.1 K), measured using millikelvin scanning tunneling microscopy. From the tunneling conductance, we extract a density of states which shows the opening of a s-wave single superconducting gap. The temperature dependence of the gap also follows BCS theory. Under magnetic fields, vortices present Caroli de Gennes Matricon states, although these are strongly broadened by defect scattering. From the vortex core size we obtain a superconducting coherence length of<i>ξ</i> = 50 nm, compatible with the value extracted from macroscopicHc2measurements. We discuss the comparison between s-wave LaRu₂P₂and pnictide unconventional multiple gap and strongly correlated Fe based superconductors.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fano resonances in gated phosphorene junctions.","authors":"K J Lamas-Martínez, J A Briones-Torres, S Molina-Valdovinos, I Rodríguez-Vargas","doi":"10.1088/1361-648X/ad8618","DOIUrl":"10.1088/1361-648X/ad8618","url":null,"abstract":"<p><p>Fano resonances appear in plenty of physical phenomena due to the interference phenomena of a continuum spectrum and discrete states. In gated bilayer graphene junctions, the chiral matching at oblique incidence between the spectrum of electron states outside the electrostatic barrier and hole bound states inside it gives rise to an asymmetric line shape in the transmission as a function of the energy or Fano resonance. Here, we show that Fano resonances are also possible in gated phosphorene junctions along the zigzag direction. The special pseudospin texture of the charge carriers in the zigzag direction allows at oblique incidence the interference phenomena of the spectrum of electron states outside the electrostatic barrier with hole bound states inside it, giving rise to an asymmetric Fano line shape in the transmission. Due to the energy scale of the electrostatic barriers in phosphorene ultra thin barriers are required to observe the Fano resonance phenomenon. The preservation of the pseudospin texture with the closing of the phosphorene band gap opens the possibility to observe Fano resonances in smaller and wider electrostatic barriers. The asymmetric Fano line shape is susceptible to the transverse wave vector, the strength and width of the electrostatic barrier. Additionally, the conductance shows a characteristic mark in the position where the Fano resonances take place. The similarities and differences with respect to Fano resonances in bilayer graphene are also addressed.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142406526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure and properties of mixed valent CeFe₂Al₈.","authors":"Nilofar Kurawle, Soumen Samanta, Shovit Bhattacharya, Sudhindra Rayaprol","doi":"10.1088/1361-648X/ad83a3","DOIUrl":"10.1088/1361-648X/ad83a3","url":null,"abstract":"<p><p>Temperature dependent magnetic, electrical transport and thermal properties of polycrystalline orthorhombic CeFe₂Al₈intermetallic compound have been studied along with its isostructural La counterpart, LaFe₂Al₈. For the cerium compound, low field<i>dc</i>magnetization exhibits an antiferromagnetic like ordering (<i>T</i>_N) ∼ 4 K. The main feature of the magnetic susceptibility plot is a broad hump spanning a large temperature range, indicating mixed valence of Ce in the compound, in good agreement with reported literature. However, contrary to the reported observations we find that the mixed valence state is very robust and was evident even up to very high magnetic fields (> 2 T). Further, in this work we report 3d core level photoemission spectra of cerium in CeFe₂Al₈, to understand the valence state of cerium ions in this system. Additionally, from resistivity measurements it is found that, CeFe₂Al₈is metallic with no indication of any anomaly, till the lowest temperature of measurement. Specific heat measurements show very low value of heat capacity and electronic contribution. The isostructural La analogue, LaFe₂Al₈compound shows broadness in susceptibility with maxima around 44 K which may be attributed to ordering of Fe moments. The comparison of Ce and La compounds brings out the role of Fe magnetic moments which may be responsible for competing with cerium moments and resulting in the dilution of long-range magnetic order, also contributing to magnetic frustration in CeFe₂Al₈.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142375593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elastic mechanical thermodynamic and thermoelectric properties of pristine and titanium doped Mg₂Si: a density functional theory study.","authors":"Pradeep Kumar Sharma, Chetan Kachhara, N Laihnuna, Sanjay Kedia","doi":"10.1088/1361-648X/ad84a9","DOIUrl":"10.1088/1361-648X/ad84a9","url":null,"abstract":"<p><p>Herein, we report a systematic investigation of the effect of Titanium doping on the structural, elastic, mechanical, thermodynamic, and thermoelectric (TE) dynamics of Mg₂Si Compounds using first-principle investigation. The present study has been carried out using the full potential linearized augmented plane wave method as implemented in<i>Wien2k</i>code under<i>mBJ</i>exchange potentials. The investigations revealed that Mg_2-<i>x</i>Ti<i>_x</i>Si compounds have structural stability with cubic phase (<i>Fm-3m</i>symmetry) and possess degenerate semiconducting nature. The analysis of elastic constants revealed mechanical stability of the investigated compounds following Born criteria. Thermodynamic investigations have been carried out in the temperature range of 100-1500 K at zero pressure and the quantities like heat capacity, Debye temperature, Grüneisen constant, and thermal expansion coefficient have been critically analyzed. Lastly, the TE performance of Mg_2-<i>x</i>Ti<i>_x</i>Si compounds has been predicted by estimating the thermopower (<i>S</i>²<i>σ</i>) and TE figure of merit (<i>zT</i>) in the temperature range of 300-1500 K. The predicted value of<i>zT</i>_maxfor Mg_2-<i>x</i>Ti<i>_x</i>Si compound is 0.67 at 800 K for<i>x</i>= 0.25 titanium content, suggesting materials promising application for TE energy harvesting and mechanical devices.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142391362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinetic energy driven two-sublattice double-exchange: a general mechanism of magnetic exchange in transition metal compounds.","authors":"Tanusri Saha-Dasgupta, Koushik Pradhan","doi":"10.1088/1361-648X/ad841a","DOIUrl":"10.1088/1361-648X/ad841a","url":null,"abstract":"<p><p>One of the most important phenomena in magnetism is the exchange interaction between magnetic centres. In this topical review, we focus on the exchange mechanism in transition-metal compounds and establish kinetic-energy-driven two-sublattice double-exchange as a general mechanism of exchange, in addition to well-known mechanisms like superexchange and double exchange. This mechanism, which was first proposed (Sarma<i>et al</i>2000<i>Phys. Rev. Lett.</i><b>85</b>2549), in the context of Sr₂FeMoO₆, a double-perovskite compound, later found to describe a large number of 3d and 4d or 5d transition metal-based double perovskites. The magnetism in multi-sublattice magnetic systems like double-double and quadrupolar perovskites involving 3d and 4d or 5d transition-metal ions have also been found to be governed by this as a primary mechanism of exchange. For example, the numerical solution of a two-sublatice double exchange with additional superexchange couplings for the FeRe-based double double and quadrupolar perovskites are found to reproduce the experimentally observed magnetic ground state as well as the high transition temperature of above 500 K. The applicability of this general mechanism extends beyond the perovskite crystal structures, and oxides, as demonstrated for the pyrochlore oxide, Tl₂Mn₂O₇and the square-net chalcogenides KMnX₂(X = S, Se, Te). The counter-intuitive doping dependence and pressure effect of magnetic transition temperature in Tl₂Mn₂O₇is explained, while KMnX₂(X = S, Se, Te) compounds are established as half-metallic Chern metals guided by two sublattice double exchange. While the kinetic energy-driven two-site double-exchange mechanism was originally proposed to explain ferromagnetism, a filling-dependent transition can lead to a rare situation of the antiferromagnetic metallic ground state, as found in La-doped Sr₂FeMoO₆, and proposed for computer predicted double perovskites Sr(Ca)₂FeRhO₆. This opens up a vast canvas to explore.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142391364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reciprocal or nonreciprocal bimolecular interface and quantum entanglement.","authors":"Xing-Chen Wang, Jing-Wei Wang, Lian-Zhen Cao, Jia-Qiang Zhao, Dong-Yan Lü, Ji-Xiang Sui, Xiu-Juan Dong, Bo Li, Guang-Hui Wang, Yuan Zhou","doi":"10.1088/1361-648X/ad81a5","DOIUrl":"10.1088/1361-648X/ad81a5","url":null,"abstract":"<p><p>We study a hybrid system of a plasmonic cavity coupled to a pair of different molecular vibration modes with the strong optomechanical-like interactions. Here, this plasmonic cavity is considered as a quantum data bus and then assist several applications. For instance, it can first establish a bimolecular interface to ensure the reciprocal or non-reciprocal information transmission, and then engineer both molecules into the steady-state quantum entanglement of the continuous variable through the dissipative method. In contrast to the traditional optomechanical system, this hybrid system can provide the stronger optomechanical-like interactions and more convenient controls to the molecular quantum units. This investigation is believed to be able to further expand the practical application range of quantum technology.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142348887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical study of point defects on transport properties in metallic interconnections.","authors":"Shumin Yan, Ruiling Gao, Shunbo Hu, Yin Wang","doi":"10.1088/1361-648X/ad83a2","DOIUrl":"https://doi.org/10.1088/1361-648X/ad83a2","url":null,"abstract":"<p><p>During the line width reduction, electron scattering caused by various defects in metal interconnects increases dramatically, which causes leakage or short circuit problems in the device, reducing device performance and reliability. Point defects are one of the important factors. Here, using density functional theory and non-equilibrium Green's function methods, we systematically study the effects of point defects on the transport properties of metals Al, Cu, Ag, Ir, Rh, and Ru, namely vacancy defects and interstitial doping of C atom. The results show that the conductivity of all systems decreases compared to perfect systems, because defects cause unnecessary electron scattering. Since the orbital hybridization of the C atom with the Al, Cu and Ag atoms is stronger than that metals Ir, Rh and Ru, the doping of C atom significantly reduces the conductivity of metals Al, Cu and Ag compared to vacancy defects. In contrast, vacancy defects have a greater impact than doping on the transport properties of metals Ir, Rh and Ru, which is mainly attributed to the larger charge transfer of the host atoms around the vacancies caused by lattice distortion. In addition, metal Rh exhibits excellent conductivity in all systems. Therefore, in order to optimize the transport properties of interconnect metals, our work points out that the doping of impurity atoms should be avoided for metals Al, Cu and Ag, while the presence of vacancy defects should be avoided for metals Ir, Rh and Ru, and Rh may be an excellent candidate material for future metal interconnects.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":"37 2","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142468314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The magnetization process of classical Heisenberg magnets with non-coplanar cuboc ground states.","authors":"Johannes Richter, Heinz-Jürgen Schmidt, Jürgen Schnack","doi":"10.1088/1361-648X/ad7fb2","DOIUrl":"10.1088/1361-648X/ad7fb2","url":null,"abstract":"<p><p>We consider a classical Heisenberg model on the kagomé and the square kagomé lattice, where at zero magnetic field non-coplanar cuboctahedral ground states with twelve sublattices exist if suitable exchange couplings are introduced between the other neighbors. Such 'cuboc ground states' are remarkable because they allow for chiral ordering. For these models, we discuss the magnetization process in an applied magnetic field<i>H</i>by both numerical and analytical methods. We find some universal properties that are present in all models. The magnetization curve<i>M</i>(<i>H</i>) usually contains only non-linear components and there is at least one magnetic field driven phase transition. Details of the<i>M</i>(<i>H</i>) curve such as the number and characteristics (continuous or discontinuous) of the phase transitions depend on the lattice and the details of the exchange between the further neighbors. Typical features of these magnetization processes can already be derived for a paradigmatic 12-spin model that we define in this work.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142348888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using ground state and excited state density functional theory to decipher 3<i>d</i>dopant defects in GaN.","authors":"Peter A Schultz, Jesse J Lutz","doi":"10.1088/1361-648X/ad7fb1","DOIUrl":"10.1088/1361-648X/ad7fb1","url":null,"abstract":"<p><p>Using ground state density functional theory (DFT) and implementing an occupation-constrained DFT (occ-DFT) for self-consistent excited state calculations, we decipher the electronic structure of the Mn dopant and other 3<i>d</i>defects in GaN across the band gap. Our analysis, validated with broad agreement with defect levels (ground-state calculations) and photoluminescence data (excited-state calculations), mandates reinterpretation and reassignment of 3<i>d</i>defect data in GaN. The Mn_Gadefect is determined to span stable charge states from (1-) in<i>n</i>-type GaN through (2+) in<i>p</i>-type GaN. The Mn(2+) is predicted to be a<i>d</i>²ground state spin triplet defect with a singlet excited state, isoelectronic with the defect associated with the 1.19 eV photoluminescence in<i>n</i>-type GaN. The combined analysis of defect levels and excited states invites reassessment of all<i>d</i>²-capable dopants in GaN. We demonstrate that the 1.19 eV defect, a candidate defect for optically controlled quantum applications, cannot be the Cr(1+) assumed in literature and instead must be the V(0). The combined ground-state/excited-state DFT analysis is shown to be able to chemically fingerprint defects.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142348892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}