Physical Review Materials最新文献

{"title":"Tuning the electronic structure of monolayer MoS2 towards metal like via vanadium doping","authors":"Dipak Maity, Rahul Sharma, Krishna Rani Sahoo, Ashique Lal, Raul Arenal, Tharangattu N. Narayanan","doi":"10.1103/physrevmaterials.8.084002","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.084002","url":null,"abstract":"Doping of two-dimensional layered semiconducting materials is becoming pivotal in tailoring their electronic properties, enabling the development of advanced electronic and optoelectronic devices, where the selection of dopant is important. Here, we demonstrate the potential of substitutional vanadium (V) doping in monolayer molybdenum disulfide (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Mo</mi><msub><mi mathvariant=\"normal\">S</mi><mn>2</mn></msub></mrow></math>) lattice in different extents leading to tunable electronic and optoelectronic properties. We found that low-level V doping (∼1 <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>at.</mtext><mspace width=\"0.16em\"></mspace><mo>%</mo></mrow></math>) induces <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>p</mi></math>-type characteristics in otherwise <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>n</mi></math>-type monolayer <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Mo</mi><msub><mi mathvariant=\"normal\">S</mi><mn>2</mn></msub></mrow></math>, whereas medium-level doping (∼5 <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>at.</mtext><mspace width=\"0.16em\"></mspace><mo>%</mo></mrow></math>) leads to an ambipolar semiconductor. Degenerately doped <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Mo</mi><msub><mi mathvariant=\"normal\">S</mi><mn>2</mn></msub></mrow></math> (∼9 <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>at.</mtext><mspace width=\"0.16em\"></mspace><mo>%</mo></mrow></math>) facilitates a transition from semiconducting towards metallic (metal-like) with reduced electrical resistivity (∼4.5 <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"normal\">Ω</mi><mspace width=\"0.16em\"></mspace><mtext>m</mtext></mrow></math> of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Mo</mi><msub><mi mathvariant=\"normal\">S</mi><mn>2</mn></msub></mrow></math> to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mo>∼</mo><mn>2.2</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup><mi mathvariant=\"normal\">Ω</mi><mspace width=\"0.16em\"></mspace><mtext>m</mtext></mrow></math>), low activation energy for transport (∼11 meV), and electric field independent drain current in field effect transistor–based transfer characteristics. A detailed temperature- and power-dependent photoluminescence study along with density functional theory–based calculations in support unravels the emergence of an excitonic transition at ∼850 nm with its intensity dependent on the amount of vanadium. This study shows the potential of V doping in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Mo</mi><msub><mi mathvariant=\"normal\">S</mi><mn>2</mn></msub></mrow></math> for generating multifunctional two-dimensional materials for next generation electronics, optoelectronics, and interconnects with systematic control over its electronic structure in a wide range.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erratum: Understanding the flat thermal conductivity of La2Zr2O7 at ultrahigh temperatures [Phys. Rev. Materials 8, 043804 (2024)]","authors":"Hao Zhou, Janak Tiwari, Tianli Feng","doi":"10.1103/physrevmaterials.8.089901","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.089901","url":null,"abstract":"<span>DOI:</span><span>https://doi.org/10.1103/PhysRevMaterials.8.089901</span>","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Local thermal expansion of Co-containing invar alloys","authors":"Toshihiko Yokoyama, Hiromichi T. Fujii, Shingo Matsumura, Naoki Sakaguchi, Naoya Kurahashi, Naoyuki Maejima","doi":"10.1103/physrevmaterials.8.083603","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.083603","url":null,"abstract":"Thermal expansion of Co-containing invar alloys of GX1Ni29-Co17 <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Fe</mi><mn>54</mn></msub><msub><mi>Co</mi><mn>17</mn></msub><msub><mi>Ni</mi><mn>29</mn></msub></mrow></math> and stainless invar <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Fe</mi><mn>39</mn></msub><msub><mi>Co</mi><mn>50</mn></msub><msub><mi>Cr</mi><mn>9</mn></msub><msub><mi>Ni</mi><mn>2</mn></msub></mrow></math> was investigated from the viewpoint of local structure by analyzing temperature-dependent extended x-ray absorption fine-structure (EXAFS) spectra combined with the computational simulations based on the path-integral effective classical potential (PIECP) method. For detailed comparative discussion, FeNi invar alloys of 36invar, 42invar, and 45invar were also examined. It is found by EXAFS that in stainless invar, Co exhibits a noticeable invar effect, while the invar effect on Co in GX1Ni29-Co17 is negligibly small. The PIECP simulations provide qualitative agreement with this finding, exemplifying that the Co magnetization is more effectively suppressed in stainless invar with a temperature rise, because of a smaller lattice constant and shorter corresponding interatomic distances. The present study clearly demonstrates the importance of the local structural point of view to understand the detailed low thermal expansion mechanism, in which microscopic local thermal expansion often meaningfully differs from macroscopic lattice thermal expansion.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insight into Janus V2COS as anode material of high-performance alkali metal ion battery: Diffusion barrier, recyclability, specific capacity, and open-circuit voltage","authors":"Fanfan Wang, Jun Yuan, Zhufeng Zhang, Baoan Song, Junhua Zhao, Jincheng Yue, Tian Xu, Jun Zhou","doi":"10.1103/physrevmaterials.8.085801","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.085801","url":null,"abstract":"Transition metal carbides, nitrides, and carbonitrides, known as MXenes, exhibit exceptional conductivity, stability, and large specific surface area, rendering them promising candidates for anode materials in rechargeable batteries. Herein, we investigate the electrochemical characteristics of the Janus MXene <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">V</mi><mn>2</mn></msub><mi>COS</mi></mrow></math> monolayer, as an anode material of alkali metal ion batteries by using first-principles calculations. The phonon band structure and <i>ab initio</i> molecular dynamics simulations confirm the stability of the Janus <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">V</mi><mn>2</mn></msub><mi>COS</mi></mrow></math> monolayer. The mechanical and electrical properties of the Janus <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">V</mi><mn>2</mn></msub><mi>COS</mi></mrow></math> monolayer are explored and proved to have good mechanical stability and electrical conductivity. The surface of the Janus <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">V</mi><mn>2</mn></msub><mi>COS</mi></mrow></math> monolayer demonstrates the facile adsorption of alkali metal ions and low diffusion barriers. As an anode material, the recyclability of the Janus <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">V</mi><mn>2</mn></msub><mi>COS</mi></mrow></math> has been verified in the ion intercalation/deintercalation processes. Furthermore, the theoretical specific capacities and the open-circuit voltages of the Janus <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">V</mi><mn>2</mn></msub><mi>COS</mi></mrow></math> monolayer are calculated to be <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>165.54</mn><mspace width=\"0.28em\"></mspace><mi>mA</mi><mspace width=\"0.16em\"></mspace><mi mathvariant=\"normal\">h</mi><mtext>/</mtext><mi mathvariant=\"normal\">g</mi></mrow></math> and 2.62 V for Li, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>662.18</mn><mspace width=\"0.28em\"></mspace><mi>mA</mi><mspace width=\"0.16em\"></mspace><mi mathvariant=\"normal\">h</mi><mtext>/</mtext><mi mathvariant=\"normal\">g</mi></mrow></math> and 0.76 V for Na, and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>294.43</mn><mspace width=\"0.28em\"></mspace><mi>mA</mi><mspace width=\"0.16em\"></mspace><mi mathvariant=\"normal\">h</mi><mtext>/</mtext><mi mathvariant=\"normal\">g</mi></mrow></math> and 0.4 V for K, respectively. It presents that the Janus <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">V</mi><mn>2</mn></msub><mi>COS</mi></mrow></math> monolayer is a potential anode material of sodium-ion batteries and potassium-ion batteries.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying local lattice distortions in refractory high-entropy alloys","authors":"Yao Hu (胡尧), Lewis R. Owen, Helen Y. Playford, Aina Edgren, Sheng Guo, Magnus Hörnqvist Colliander","doi":"10.1103/physrevmaterials.8.083602","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.083602","url":null,"abstract":"Severe local lattice distortions (LLDs), originating from the size mismatch among atoms, have been proposed as one of the key mechanisms responsible for the excellent mechanical properties of bcc-structured high-entropy alloys (HEAs). They have also been connected to phase stability, as well as physical properties such as electrical conductivity. Experimental measurements of LLDs are, however, difficult and often ambiguous. Analysis of total scattering data in real space has been proposed to provide a uniquely suitable probe of LLDs, but its widespread application and validation are still limited. We conduct a thorough study of LLD measurements in refractory high-entropy alloys (RHEAs) using small-box pair distribution function (PDF) analysis. We start by reexamining existing literature data using a recently proposed coherent theoretical framework to demonstrate that LLDs in RHEAs can indeed be considered as severe and can be reliably measured even in the absence of known thermal components. We perform total scattering experiments of a typical RHEA (HfNbTaTiZr) using both x-rays and neutrons, and show that real-space PDF analysis of data from different types of radiation gives consistent values of LLDs. The results are also in good agreement with the values derived from reciprocal-space data. Finally, through simulation and analysis of theoretical two-phase PDFs, we demonstrate that the effect of the chemical segregation in the investigated RHEA on the measured LLDs is limited when dealing with comparatively large LLDs. The results show that PDF analysis using small-box modeling provides a fast and reliable tool for measuring LLDs in RHEAs, which makes it ideal for analysis of large data sets from time-resolved <i>in situ</i> measurements.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ferroelectricity and piezoelectricity in elemental α-X6 structure","authors":"Xuanlin Zhang, Luqi Dong, Yunhao Lu","doi":"10.1103/physrevmaterials.8.084401","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.084401","url":null,"abstract":"Two-dimensional (2D) elemental ferroelectricity has recently been confirmed and arouses great interest in exploring new elemental asymmetric structures and their symmetry-breaking related properties. In this study, our density functional theory (DFT) calculations reveal the existence of coupled in-plane and out-of-plane electric polarizations in the group <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">V</mi></math> elements <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>α</mi><mtext>−</mtext><mrow><mi>X</mi></mrow><mn>6</mn></math> (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"italic\">X</mi><mo>=</mo><mi mathvariant=\"normal\">P</mi></mrow></math>, As). These ferroelectric phases are stabilized through charge transfer between <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>p</mi><mi mathvariant=\"normal\">x</mi></msub></math> orbitals. The introduction of compressive strain facilitates the transformation from blue phosphorene into <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>α</mi></math>-P6 phase with low reaction energy owing to their structural similarity. In addition, strain engineering or atom substitution can effectively reduce the polarization switching barrier. Furthermore, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>α</mi><mtext>−</mtext><mrow><mi>X</mi></mrow><mn>6</mn></math> structure exhibits large longitudinal piezoelectric strain coefficients <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>d</mi><mn>11</mn></msub></math>, benefiting from their moderate <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>e</mi><mn>11</mn></msub></math> and flexible character. This discovery not only enriches the family of elemental ferroelectrics but also deepens the understanding of the origin of elemental polarization, offering potential candidates for ferroelectric and piezoelectric applications.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observation of a second Dirac point in a graphene/superconductor bilayer","authors":"Gopi Nath Daptary, Eyal Walach, Udit Khanna, Efrat Shimshoni, Aviad Frydman","doi":"10.1103/physrevmaterials.8.084802","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.084802","url":null,"abstract":"Two-dimensional (2D) materials have attracted vast research interest since the breakthrough discovery of graphene. One major benefit of such systems is the ability to tune the Fermi level through the charge neutrality point between electron and hole doping. Here we show that single layer graphene coupled to the low-density superconductor indium oxide (InO) exhibits two charge neutrality points, each of them representing electronic regions in which the carrier density can be tuned from hole to electron dominated. This is not seen in clean graphene or in a bilayer where the carrier density is extremely low. We suggest that the second charge neutrality point results from regions in the graphene layer just below superconducting islands in InO, where pairing is induced via the proximity effect; gating of this hybrid system therefore allows the tuning from hole to electron superconductivity through an ultralow carrier density regime. We propose this as a “superconducting Dirac point (SDP)” where intravalley scattering is greatly enhanced. Our results suggest that the electronic states around SDP behave like those in a strongly coupled superconductor.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanocrystalline tungsten at high radiation exposure","authors":"Pui-Wai Ma, Daniel R. Mason, Steven Van Boxel, Sergei L. Dudarev","doi":"10.1103/physrevmaterials.8.083601","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.083601","url":null,"abstract":"Evolution of nanocrystalline (NC) tungsten under radiation exposure is investigated by atomic scale simulations in the low temperature high dose limit. Statistical analysis of samples containing at least a million atoms, with grain size varying from 5 nm to 20 nm, shows that the pattern of microstructural evolution of a NC material differs significantly from that of a single crystal. The high resistance to swelling in the low grain size limit stems from a combined effect of the initial excess volume of atomic configurations at grain boundaries and high integral volume of grain boundary defect-denuded zones. Grain boundaries annihilate defects through the rearrangement of their local atomic configurations acting as fluctuating dynamic sinks for defects. Grain size distribution slowly broadens as a function of dose, delaying the onset of an asymptotic radiation-driven steady state in comparison with a single crystalline material. Spatial limitations imposed by the size and topology of grains prevent the formation of a percolating dislocation network, resulting in only isolated dislocation loops being retained in the microstructure even at high radiation exposure.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Nb alloying on Nb recrystallization and the upper critical field of Nb3Sn","authors":"Nawaraj Paudel, Chiara Tarantini, Shreyas Balachandran, William L. Starch, Peter J. Lee, David C. Larbalestier","doi":"10.1103/physrevmaterials.8.084801","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.084801","url":null,"abstract":"<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">Nb</mi><mn>3</mn></msub><mi>Sn</mi></mrow></math> conductors are important candidates for high-field magnets for particle accelerators, and they continue to be widely used for many laboratory and nuclear magnetic resonance magnets. However, the critical current density, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>J</mi><mi>c</mi></msub></math>, of present <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">Nb</mi><mn>3</mn></msub><mi>Sn</mi></mrow></math> conductors declines swiftly above 12–15 T. State-of-the-art Ta- and Ti-doped strands exhibit upper critical field, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>H</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub></math>, values of ∼24–26.5 T (4.2 K) and do not reach the Future Circular Collider target <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>J</mi><mi>c</mi></msub></math>, which serves as the present stretch target for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">Nb</mi><mn>3</mn></msub><mi>Sn</mi></mrow></math> development. As recently demonstrated, to meet this goal requires enhanced vortex pinning but an independent and supplementary approach is to significantly enhance <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>H</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub></math>. In this study, we have arc melted multiple Nb alloys with added Hf, Zr, Ta, and Ti and drawn them successfully into monofilament wires to investigate the possibilities of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>H</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub></math> enhancement through alloying. <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>H</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub><mo>(</mo><mi>T</mi><mo>)</mo></math> was measured for all samples in fields up to 16 T and some up to 31 T. We have found that all alloys show good agreement with the standard Werthamer, Helfand, and Hohenberg fitting procedure without the need to adjust the paramagnetic limitation parameter (<i>α</i>) and spin-orbit scattering parameter <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>(</mo><msub><mi>λ</mi><mi>so</mi></msub><mo>)</mo></math>. The evaluation of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>d</mi><msub><mi>H</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub><mo>/</mo><mi>d</mi><mi>T</mi></mrow></math> near <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mi>c</mi></msub></math>, which is proportional to the electronic specific heat coefficient <i>γ</i> and the normal state resistivity <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>ρ</mi><mi mathvariant=\"normal\">n</mi></msub></math>, allows a better understanding of the induced disorder introduced by alloying in the A15 phase. So far, we have observed that Hf alloying of pure Nb can enhance <math xmln","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tuning the quantum phase transition of an ultrathin magnetic topological insulator","authors":"Mohammad Shafiei, Farhad Fazileh, François M. Peeters, Milorad V. Milošević","doi":"10.1103/physrevmaterials.8.074201","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.074201","url":null,"abstract":"We explore the effect of thickness, magnetization direction, strain, and gating on the topological quantum phase transition of a thin-film magnetic topological insulator. Reducing the film thickness to the ultrathin regime couples the edge states on the two surfaces, opening a gap known as the hybridization gap, and causing a phase transition from a topological insulator to a normal insulator (NI). An out-of-plane/in-plane magnetization of size proportional to the hybridization gap triggers a phase transition from a normal insulator state to a quantum anomalous Hall (QAH)/semimetal state. A magnetization tilt by angle <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>θ</mi></math> from the out-of-plane axis influences the topological phase transition in a way that for sufficiently large <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>θ</mi></math>, no phase transition from NI to QAH can be observed regardless of the sample thickness or magnetization, and for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>θ</mi></math> close to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>π</mi><mo>/</mo><mn>2</mn></mrow></math> the system transits to a semimetal phase. Furthermore, we demonstrate that compressive/tensile strain can be used to decrease/increase the magnetization threshold for the topological phase transition. Finally, we reveal the effect of a vertical potential acting on the film, be it due to the substrate or applied gating, which breaks inversion symmetry and raises the magnetization threshold for the transition from NI to QAH state.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}