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Point defects in CdTe and CdTeSe alloy: A first principles investigation with DFT+U 碲化镉和碲化镉合金中的点缺陷:利用 DFT+U 的第一原理研究
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-28 DOI: 10.1103/physrevmaterials.8.084602
Xiaofeng Xiang, Yijun Tong, Aaron Gehrke, Scott T. Dunham
CdTe and its alloy CdSeTe are widely used in optoelectronic devices, such as radiation detectors and solar cells, due to their superior electrical properties. However, the formation of defects and defect complexes in these materials can significantly affect their performance. As a result, understanding the defect formation and recombination processes in CdTe and CdSeTe alloy is of great importance. In recent years, density functional theory (DFT) calculations have emerged as a powerful tool for investigating the properties of defects in semiconductors. In this paper, we use DFT+U calculations to comprehensively study the properties of intrinsic defects as well as extrinsic defects induced by commonly used dopants, such as Cu and group V elements, in CdTe and CdSeTe alloy. This work provides insights into the effects of these defects on the electrical and optical properties of the material.
碲化镉及其合金碲化镉因其优异的电气性能而被广泛应用于光电设备,如辐射探测器和太阳能电池。然而,这些材料中缺陷和缺陷复合物的形成会严重影响其性能。因此,了解 CdTe 和 CdSeTe 合金中的缺陷形成和重组过程非常重要。近年来,密度泛函理论(DFT)计算已成为研究半导体缺陷特性的有力工具。本文利用 DFT+U 计算全面研究了 CdTe 和 CdSeTe 合金中铜和 V 族元素等常用掺杂剂诱导的本征缺陷和外征缺陷的性质。这项研究深入揭示了这些缺陷对材料电学和光学特性的影响。
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引用次数: 0
Low-energy modeling of three-dimensional topological insulator nanostructures 三维拓扑绝缘体纳米结构的低能建模
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-28 DOI: 10.1103/physrevmaterials.8.084204
Eduárd Zsurka, Cheng Wang, Julian Legendre, Daniele Di Miceli, Llorenç Serra, Detlev Grützmacher, Thomas L. Schmidt, Philipp Rüßmann, Kristof Moors
We develop an accurate nanoelectronic modeling approach for realistic three-dimensional topological insulator nanostructures and investigate their low-energy surface-state spectrum. Starting from the commonly considered four-band k·p bulk model Hamiltonian for the Bi2Se3 family of topological insulators, we derive new parameter sets for Bi2Se3, Bi2Te3, and Sb2Te3. We consider a fitting strategy applied to ab initio band structures around the Γ point that ensures a quantitatively accurate description of the low-energy bulk and surface states while avoiding the appearance of unphysical low-energy states at higher momenta, something that is not guaranteed by the commonly considered perturbative approach. We analyze the effects that arise in the low-energy spectrum of topological surface states due to band anisotropy and electron-hole asymmetry, yielding Dirac surface states that naturally localize on different side facets. In the thin-film limit, when surface states hybridize through the bulk, we resort to a thin-film model and derive thickness-dependent model parameters from ab initio calculations that show good agreement with experimentally resolved band structures, unlike the bulk model that neglects relevant many-body effects in this regime. Our versatile modeling approach offers a reliable starting point for accurate simulations of realistic topological material-based nanoelectronic devices.
我们为现实的三维拓扑绝缘体纳米结构开发了一种精确的纳米电子建模方法,并研究了它们的低能表面态谱。从通常认为的 Bi2Se3 系列拓扑绝缘体的四带 k-p 体模型哈密顿开始,我们得出了 Bi2Se3、Bi2Te3 和 Sb2Te3 的新参数集。我们考虑将拟合策略应用于 Γ 点附近的 ab initio 带状结构,以确保定量准确地描述低能体态和表面态,同时避免在较高的时刻出现非物理的低能态,而这是通常认为的微扰方法所无法保证的。我们分析了拓扑表面态的低能谱中由于能带各向异性和电子-空穴不对称而产生的效应,这些效应产生的狄拉克表面态自然地局域在不同的侧刻面上。在薄膜极限,当表面态通过体层发生杂化时,我们采用薄膜模型,并通过原子序数计算推导出厚度相关的模型参数,这些参数与实验解析的能带结构显示出良好的一致性,而不像体层模型在这一机制中忽略了相关的多体效应。我们的多功能建模方法为精确模拟基于拓扑材料的现实纳米电子器件提供了一个可靠的起点。
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引用次数: 0
Magnetic phase dependency of the thermal conductivity of FeRh from thermoreflectance experiments and numerical simulations 从热反射实验和数值模拟看 FeRh 热导率的磁相依赖性
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-28 DOI: 10.1103/physrevmaterials.8.084411
A. Castellano, K. Alhada-Lahbabi, J. A. Arregi, V. Uhlíř, B. Perrin, C. Gourdon, D. Fournier, M. J. Verstraete, L. Thevenard
FeRh is well known in its bulk form for a temperature-driven antiferromagnetic (AFM) to ferromagnetic (FM) transition near room temperature. It has aroused renewed interest in its thin-film form, with particular focus on its biaxial AFM magnetic anisotropy which could serve for data encoding, and the possibility to investigate laser-assisted phase transitions, with varying contributions from electrons, phonons, and magnons. In order to estimate the typical temperature increase occurring in these experiments, we performed modulated thermoreflectance microscopy to determine the thermal conductivity κ of FeRh. As often occurs upon alloying, and despite the good crystallinity of the layer, κ was found to be lower than the thermal conductivities of its constituting elements. More unexpectedly, given the electrically more conducting nature of the FM phase, it turned out to be three times lower in the FM phase compared to the AFM phase. This trend was confirmed by examining the temporal decay of incoherent phonons generated by a pulsed laser in both phases. To elucidate these results, first- and second-principles simulations were performed to estimate the phonon, magnon, and electron contributions to the thermal conductivity. They were found to be of the same order of magnitude, and to give a quantitative rendering of the experimentally observed κAFM. In the FM phase, however, simulations overestimate the low experimental values, implying very different (shorter) electron and magnon lifetimes.
众所周知,FeRh 在接近室温时会发生由温度驱动的反铁磁(AFM)到铁磁(FM)的转变。它的薄膜形式再次引起了人们的兴趣,尤其是它的双轴 AFM 磁各向异性(可用于数据编码),以及在电子、声子和磁子的不同贡献下研究激光辅助相变的可能性。为了估算这些实验中出现的典型温升,我们使用了调制热反射显微镜来测定 FeRh 的热导率 κ。与合金化时经常出现的情况一样,尽管该层具有良好的结晶性,κ 仍低于其组成元素的热导率。更出乎意料的是,由于调频相的导电性更强,结果发现调频相的κ比原子力显微镜相低三倍。通过研究脉冲激光在两种相中产生的非相干声子的时间衰减,证实了这一趋势。为了阐明这些结果,我们进行了第一和第二原理模拟,以估算声子、磁子和电子对热导率的贡献。结果发现它们的数量级相同,并能定量呈现实验观察到的κAFM。然而,在调频阶段,模拟结果高估了较低的实验值,这意味着电子和磁子的寿命非常不同(较短)。
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引用次数: 0
Single crystal growth, chemical defects, magnetic and transport properties of antiferromagnetic topological insulators (Ge1−δ−xMnx)2Bi2Te5 (x≤0.47, 0.11≤δ≤0.20) 反铁磁拓扑绝缘体 (Ge1-δ-xMnx)2Bi2Te5 (x≤0.47, 0.11≤δ≤0.20) 的单晶生长、化学缺陷、磁性和输运特性
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-27 DOI: 10.1103/physrevmaterials.8.084203
Tiema Qian, Chaowei Hu, J. Green, Erxi Feng, Huibo Cao, Ni Ni
Magnetic topological insulators provide a platform for emergent phenomena arising from the interplay between magnetism and band topology. Here we report the single crystal growth, crystal structure, magnetic and transport properties, as well as the neutron scattering studies of topological insulator series (Ge1δxMnx)2Bi2Te5 (x0.47, 0.11δ0.20). Upon doping up to x=0.47, the lattice parameter c decreases by 0.8%, while the lattice parameter a remains nearly unchanged. Significant Ge vacancies and Ge/Bi site mixing are revealed via elemental analysis as well as refinements of the neutron and x-ray diffraction data, resulting in holes dominating the charge transport. At x=0.47, below 10.8 K, a bilayer A-type antiferromagnetic ordered state emerges, featuring an ordered moment of 3.0(3) μB/Mn at 5 K, with the c axis as the easy axis. Magnetization data unveils a much stronger effective interlayer antiferromagnetic exchange interaction and a much smaller uniaxial anisotropy compared to MnBi2Te4. We attribute the former to the shorter nearest-neighbor Mn-Mn interlayer superexchange path and the latter to the smaller ligand-field splitting in (Ge1δxMnx)2Bi2Te5. Our study demonstrates that this series of materials holds promise for the investigation of the layer Hall effect and quantum metric nonlinear Hall effect.
磁性拓扑绝缘体为磁性和带拓扑之间的相互作用所产生的新现象提供了一个平台。在此,我们报告了拓扑绝缘体系列 (Ge1-δ-xMnx)2Bi2Te5 (x≤0.47, 0.11≤δ≤0.20) 的单晶生长、晶体结构、磁性和输运性质以及中子散射研究。掺杂到 x=0.47 时,晶格参数 c 下降了 0.8%,而晶格参数 a 几乎保持不变。通过元素分析以及对中子和 X 射线衍射数据的改进,发现了大量的 Ge 空位和 Ge/Bi 位点混合,从而导致空穴主导了电荷传输。在 x=0.47 时,温度低于 10.8 K,出现了双层 A 型反铁磁有序态,5 K 时的有序矩为 3.0(3) μB/Mn,c 轴为易轴。与锰铋碲 4 相比,磁化数据揭示了更强的有效层间反铁磁交换相互作用和更小的单轴各向异性。我们将前者归因于更短的近邻锰-锰层间超交换路径,将后者归因于 (Ge1-δ-xMnx)2Bi2Te5 中更小的配位体-场分裂。我们的研究表明,这一系列材料有望用于研究层霍尔效应和量子度量非线性霍尔效应。
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引用次数: 0
Augmented chalcopyrites: A search for new Cu-In-Te phases 增生黄铜矿:寻找新的铜锡合金相
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-26 DOI: 10.1103/physrevmaterials.8.083801
Andy Paul Chen, Wei Nong, Maung Thway, Jose Recatala-Gomez, Haiwen Dai, Wenhao Zhai, D. V. Maheswar Repaka, Kedar Hippalgaonkar
Chalcopyrites are ternary crystalline compounds which have found use in a diverse array of applications, from solar cells to thermoelectric devices. These are known to be ternary-compound analogs to diamond or sphalerite. “Defect chalcopyrites,” which are chalcopyrite structures stabilized with ordered vacancies and substitutions, are well attested and can serve as a method of tuning material properties through control of stoichiometry. In particular, defect chalcopyrites related to the thermoelectric compound CuInTe2 comprise a large range of compositions in the pseudobinary system (Cu2Te)x(In2Te3)1x, where x<0.5. In contrast, the converse case of “augmented chalcopyrites,” namely, x>0.5, is much less known or studied. We report the discovery of a range of Cu2Te-rich compositions in this binary system where stable phases can potentially be found. Here, the stoichometry of augmented chalcopyrites is likely to be modulated by the concentration of defect clusters [CuIn2·2Cui+]0 in chalcopyrite CuInTe2.
黄铜矿是一种三元晶体化合物,已被广泛应用于太阳能电池和热电设备等领域。众所周知,它们是金刚石或闪锌矿的三元化合物类似物。"缺陷黄铜矿 "是一种用有序空位和置换稳定的黄铜矿结构,已得到充分证实,可作为一种通过控制化学计量来调整材料特性的方法。特别是,与热电化合物 CuInTe2 有关的缺陷黄铜矿在假二元系统 (Cu2Te)x(In2Te3)1-x 中包含大量成分,其中 x<0.5.与此相反,人们对 "增强黄铜矿 "的相反情况,即 x>0.5 的了解和研究要少得多。我们报告了在这种二元体系中发现的一系列富含 Cu2Te 的成分,在这些成分中可能存在稳定的相。在这里,增强黄铜矿的稳态测量可能受到黄铜矿 CuInTe2 中缺陷簇 [CuIn2--2Cui+]0 浓度的调节。
{"title":"Augmented chalcopyrites: A search for new Cu-In-Te phases","authors":"Andy Paul Chen, Wei Nong, Maung Thway, Jose Recatala-Gomez, Haiwen Dai, Wenhao Zhai, D. V. Maheswar Repaka, Kedar Hippalgaonkar","doi":"10.1103/physrevmaterials.8.083801","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.083801","url":null,"abstract":"Chalcopyrites are ternary crystalline compounds which have found use in a diverse array of applications, from solar cells to thermoelectric devices. These are known to be ternary-compound analogs to diamond or sphalerite. “Defect chalcopyrites,” which are chalcopyrite structures stabilized with ordered vacancies and substitutions, are well attested and can serve as a method of tuning material properties through control of stoichiometry. In particular, defect chalcopyrites related to the thermoelectric compound <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>CuInTe</mi><mn>2</mn></msub></math> comprise a large range of compositions in the pseudobinary system <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mrow><mo>(</mo><msub><mi>Cu</mi><mn>2</mn></msub><mi>Te</mi><mo>)</mo></mrow><mi>x</mi></msub><msub><mrow><mo>(</mo><msub><mi>In</mi><mn>2</mn></msub><msub><mi>Te</mi><mn>3</mn></msub><mo>)</mo></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></mrow></math>, where <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>&lt;</mo><mn>0.5</mn></mrow></math>. In contrast, the converse case of “augmented chalcopyrites,” namely, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>&gt;</mo><mn>0.5</mn></mrow></math>, is much less known or studied. We report the discovery of a range of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Cu</mi><mn>2</mn></msub><mi>Te</mi></mrow></math>-rich compositions in this binary system where stable phases can potentially be found. Here, the stoichometry of augmented chalcopyrites is likely to be modulated by the concentration of defect clusters <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><mo>[</mo><msubsup><mrow><mi>Cu</mi></mrow><mtext>In</mtext><mrow><mn>2</mn><mo>−</mo></mrow></msubsup><mo>·</mo><mn>2</mn><msubsup><mi>Cu</mi><mi>i</mi><mo>+</mo></msubsup><mo>]</mo></mrow><mn>0</mn></msup></math> in chalcopyrite <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>CuInTe</mi><mn>2</mn></msub></math>.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206130","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}
引用次数: 0
No extraordinary χ(3) in lead-halide perovskites: placing an upper bound on Kerr nonlinearity by means of time-resolved interferometry 铅卤化物过氧化物中没有非同寻常的 χ(3):通过时间分辨干涉测量法确定克尔非线性的上限
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-23 DOI: 10.1103/physrevmaterials.8.085403
Dusan Lorenc, Ayan Zhumekenov, Osman M. Bakr, Zhanybek Alpichshev
Lead halide perovskites have recently been reported to demonstrate an exceptionally high nonlinear (Kerr) refractive index n2 of up to 108cm2/W in CH3NH3PbBr3. Other researchers, however, observe different, substantially more conservative numbers. In order to resolve this disagreement, the nonlinear Kerr index of a bulk sample of lead halide perovskite was measured directly by means of an interferometer. This approach has many advantages as compared to the more standard z-scan technique. In particular, this method allows studying the induced changes to the refractive index in a time-resolved manner, thus enabling to separate the different contributions to n2. The extracted n2 values for CsPbBr3 and MAPbBr3 at λ1µm are n2=+2.1×1014cm2/W and n2=+6×1015cm2/W, respectively. Hence, these values are substantially lower than what has been indicated in most of the previous reports, implying the latter one should be regarded with great care.
最近有报道称,在 CH3NH3PbBr3 中,卤化铅包晶石显示出极高的非线性(克尔)折射率 n2,高达 10-8cm2/W。然而,其他研究人员却观察到了不同的、更为保守的数字。为了解决这一分歧,我们使用干涉仪直接测量了块状卤化铅包晶石样品的非线性克尔折射率。与更标准的 Z 扫描技术相比,这种方法有很多优点。特别是,这种方法能够以时间分辨的方式研究折射率的诱导变化,从而分离出对 n2 的不同贡献。在 λ≈1µm 处,CsPbBr3 和 MAPbBr3 的 n2 值分别为 n2=+2.1×10-14cm2/W 和 n2=+6×10-15cm2/W。因此,这些数值大大低于之前大多数报告中显示的数值,这意味着后一个数值应引起高度重视。
{"title":"No extraordinary χ(3) in lead-halide perovskites: placing an upper bound on Kerr nonlinearity by means of time-resolved interferometry","authors":"Dusan Lorenc, Ayan Zhumekenov, Osman M. Bakr, Zhanybek Alpichshev","doi":"10.1103/physrevmaterials.8.085403","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.085403","url":null,"abstract":"Lead halide perovskites have recently been reported to demonstrate an exceptionally high nonlinear (Kerr) refractive index <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"normal\">n</mi><mn>2</mn></msub></math> of up to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mn>10</mn><mrow><mo>−</mo><mn>8</mn></mrow></msup><mspace width=\"4pt\"></mspace><msup><mrow><mi>cm</mi></mrow><mn>2</mn></msup><mo>/</mo><mi mathvariant=\"normal\">W</mi></mrow></math> in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>CH</mi><mn>3</mn></msub><msub><mi>NH</mi><mn>3</mn></msub><msub><mi>PbBr</mi><mn>3</mn></msub></mrow></math>. Other researchers, however, observe different, substantially more conservative numbers. In order to resolve this disagreement, the nonlinear Kerr index of a bulk sample of lead halide perovskite was measured directly by means of an interferometer. This approach has many advantages as compared to the more standard z-scan technique. In particular, this method allows studying the induced changes to the refractive index in a time-resolved manner, thus enabling to separate the different contributions to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>n</mi><mn>2</mn></msub></math>. The extracted <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"italic\">n</mi><mn>2</mn></msub></math> values for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>CsPbBr</mi><mn>3</mn></msub></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>MAPbBr</mi><mn>3</mn></msub></math> at <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>λ</mi><mo>≈</mo><mn>1</mn><mspace width=\"0.16em\"></mspace><mi>µ</mi><mi mathvariant=\"normal\">m</mi></mrow></math> are <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>n</mi><mn>2</mn></msub><mo>=</mo><mo>+</mo><mn>2.1</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>14</mn></mrow></msup><mspace width=\"4pt\"></mspace><msup><mrow><mi>cm</mi></mrow><mn>2</mn></msup><mo>/</mo><mi mathvariant=\"normal\">W</mi></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>n</mi><mn>2</mn></msub><mo>=</mo><mo>+</mo><mn>6</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>15</mn></mrow></msup><mspace width=\"4pt\"></mspace><msup><mrow><mi>cm</mi></mrow><mn>2</mn></msup><mo>/</mo><mi mathvariant=\"normal\">W</mi></mrow></math>, respectively. Hence, these values are substantially lower than what has been indicated in most of the previous reports, implying the latter one should be regarded with great care.","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206138","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}
引用次数: 0
Crystal growth and evolution of magnetism in the EuCuP-EuCuAs solid solution EuCuP-EuCuAs 固溶体中的晶体生长和磁性演变
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-23 DOI: 10.1103/physrevmaterials.8.084410
Andrew F. May, Eleanor M. Clements, Xiaoping Wang, Heda Zhang, Brenden R. Ortiz
The hexagonal <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Eu</mi><mi>M</mi><mi>X</mi></mrow></math> <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo><mi>M</mi><mo>=</mo><mi>Cu</mi><mo>,</mo><mo> </mo><mi>Ag</mi><mo>,</mo><mo> </mo><mi>Au</mi><mo>;</mo><mo> </mo><mi>X</mi><mo>=</mo><mi mathvariant="normal">P</mi><mo>,</mo><mo> </mo><mi>As</mi><mo>,</mo><mo> </mo><mi>Sb</mi><mo>,</mo><mo> </mo><mi>Bi</mi><mo>)</mo></mrow></math> compounds host interesting electronic and magnetic properties, with seemingly intertwined topology and transport properties. One key feature of such behavior is the nature of the ordered magnetic structure. In EuCuAs, a topological Hall effect is caused by a conical spin structure that emerges when a field is applied within the easy-plane <math xmlns="http://www.w3.org/1998/Math/MathML"><mo>(</mo><mi>H</mi></math> <math xmlns="http://www.w3.org/1998/Math/MathML"><mo>⊥</mo></math> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>c</mi><mo>)</mo></math> of the helical ground state that exists below the Neel temperature of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>T</mi><mi>N</mi></msub><mo>=</mo><mn>14</mn><mspace width="0.16em"></mspace><mi mathvariant="normal">K</mi></mrow></math>. On the other hand, EuCuP is an easy-axis ferromagnet with a Curie temperature <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>T</mi><mi>C</mi></msub></math> near 31 K. Here, we investigate the evolution of the magnetic properties in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>EuCuAs</mi><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub><msub><mi mathvariant="normal">P</mi><mi>x</mi></msub></mrow></math> single crystals with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>0.16</mn><mo> </mo><mo>≤</mo><mi>x</mi><mo>≤</mo><mo> </mo><mn>0.75</mn></mrow></math>. Crystals grown by cooling slowly in a Sn flux possessed macroscale inhomogeneity of As/P, particularly for arsenic-rich crystals. However, growth in a Sn flux via an isothermal dwell at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>600</mn><msup><mspace width="0.16em"></mspace><mo>∘</mo></msup><mi mathvariant="normal">C</mi></mrow></math> produced crystals that were homogeneous within the resolution of the probes utilized to investigate these crystals. The unit cell volumes, Curie-Weiss temperatures, and magnetic transitions trend linearly with composition and the magnetic anisotropy is reduced in the alloys. The magnetization data of crystals with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>x</mi><mo>=</mo><mn>0.16</mn></mrow></math> and 0.24 indicate an easy-plane antiferromagnetic ground state while behavior similar to ferromagnetism is observed for crystals with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>x</mi><mspace width="4pt"></mspace><mo>≥</mo><mo> </mo><mn>0.41</mn></mrow></math>. The temperature-dependent magnetization data possess multiple
六方 EuMX(M=Cu、Ag、Au;X=P、As、Sb、Bi)化合物具有有趣的电子和磁性能,其拓扑结构和传输特性似乎相互交织。这种行为的一个关键特征是有序磁结构的性质。在 EuCuAs 中,当在 TN=14K 的尼尔温度以下存在的螺旋基态的易面(H⊥c)内施加磁场时,锥形自旋结构会产生拓扑霍尔效应。另一方面,EuCuP 是一种易轴铁磁体,居里温度 TC 接近 31 K。在此,我们研究了 0.16 ≤x≤ 0.75 的 EuCuAs1-xPx 单晶的磁性能演变。在锡通量中缓慢冷却生长的晶体具有 As/P 的宏观不均匀性,尤其是富砷晶体。然而,通过在 600∘C等温停留的锡通量中生长产生的晶体,在用于研究这些晶体的探针的分辨率范围内是均匀的。单胞体积、居里-韦斯温度和磁性转变随成分的变化呈线性趋势,合金中的磁各向异性有所降低。x=0.16 和 0.24 晶体的磁化数据表明其处于易平面反铁磁基态,而 x≥ 0.41 晶体的磁化行为则类似于铁磁性。在 EuCuAs0.75P0.25 附近的成分中,随温度变化的磁化数据具有多重转变,揭示了相图中这一富砷区域基态的竞争。EuCuP 的中子衍射数据也被作为先前结果的后续,先前的结果表明在 TC 时存在两步转变;观察到的数据与 T=5K 时的铁磁阶一致。
{"title":"Crystal growth and evolution of magnetism in the EuCuP-EuCuAs solid solution","authors":"Andrew F. May, Eleanor M. Clements, Xiaoping Wang, Heda Zhang, Brenden R. Ortiz","doi":"10.1103/physrevmaterials.8.084410","DOIUrl":"https://doi.org/10.1103/physrevmaterials.8.084410","url":null,"abstract":"The hexagonal &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;mi&gt;Eu&lt;/mi&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt; &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;Cu&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mi&gt;Ag&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mi&gt;Au&lt;/mi&gt;&lt;mo&gt;;&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi mathvariant=\"normal\"&gt;P&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mi&gt;As&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mi&gt;Sb&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mi&gt;Bi&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt; compounds host interesting electronic and magnetic properties, with seemingly intertwined topology and transport properties. One key feature of such behavior is the nature of the ordered magnetic structure. In EuCuAs, a topological Hall effect is caused by a conical spin structure that emerges when a field is applied within the easy-plane &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/math&gt; &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mo&gt;⊥&lt;/mo&gt;&lt;/math&gt; &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt; of the helical ground state that exists below the Neel temperature of &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;14&lt;/mn&gt;&lt;mspace width=\"0.16em\"&gt;&lt;/mspace&gt;&lt;mi mathvariant=\"normal\"&gt;K&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;. On the other hand, EuCuP is an easy-axis ferromagnet with a Curie temperature &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;msub&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt; near 31 K. Here, we investigate the evolution of the magnetic properties in &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;EuCuAs&lt;/mi&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mi mathvariant=\"normal\"&gt;P&lt;/mi&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt; single crystals with &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;mn&gt;0.16&lt;/mn&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mn&gt;0.75&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;. Crystals grown by cooling slowly in a Sn flux possessed macroscale inhomogeneity of As/P, particularly for arsenic-rich crystals. However, growth in a Sn flux via an isothermal dwell at &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;mn&gt;600&lt;/mn&gt;&lt;msup&gt;&lt;mspace width=\"0.16em\"&gt;&lt;/mspace&gt;&lt;mo&gt;∘&lt;/mo&gt;&lt;/msup&gt;&lt;mi mathvariant=\"normal\"&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt; produced crystals that were homogeneous within the resolution of the probes utilized to investigate these crystals. The unit cell volumes, Curie-Weiss temperatures, and magnetic transitions trend linearly with composition and the magnetic anisotropy is reduced in the alloys. The magnetization data of crystals with &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0.16&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt; and 0.24 indicate an easy-plane antiferromagnetic ground state while behavior similar to ferromagnetism is observed for crystals with &lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mspace width=\"4pt\"&gt;&lt;/mspace&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;mo&gt; &lt;/mo&gt;&lt;mn&gt;0.41&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;. The temperature-dependent magnetization data possess multiple","PeriodicalId":20545,"journal":{"name":"Physical Review Materials","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206134","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}
引用次数: 0
Low-intensity illumination induced relaxation and charge transport behavior of single crystal halide perovskites 单晶卤化物过氧化物的低强度照明诱导弛豫和电荷传输行为
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-23 DOI: 10.1103/physrevmaterials.8.085404
Avisek Maity, Sudipta Chatterjee, Barnali Ghosh, A. K. Raychaudhuri
We have investigated impedance, electric modulus, and dielectric spectroscopies, along with AC conductivity, on single crystals of methylammonium lead iodide (MAPI) and formamidinium lead iodide (FAPI) in the frequency range 50Hzf1MHz in the dark and under low-intensity illumination (80µW/cm2). It is demonstrated that the relaxation observed in this frequency range in these single crystals can be attributed to space charge effects in the bulk of the crystals, which are caused by the finite time scale associated with charge relaxation, which can occur in this frequency range due to the large static dielectric constant and low conductivity of these solids. The relaxation was found to be faster in FAPI (with higher conductivity) compared to that in MAPI (with lower conductivity). The electron-hole pair generated by illumination enhances electronic conductivity and accelerates ionic migration by lowering the barrier; this, in turn, decreases the charge relaxation time and enhances the relaxation process. The barrier lowering inferred from the reduction in relaxation times by illumination is proposed to be associated with changes in the chemical potential attributed to carrier generation.
我们对碘化甲铵铅 (MAPI) 和碘化甲脒铅 (FAPI) 的单晶体进行了阻抗、电模量和介电光谱以及交流电导率的研究,研究频率范围为 50Hz≤f≤1MHz,在黑暗环境和低强度照明(≤80µW/cm2)下进行。研究表明,在这一频率范围内观察到的这些单晶体的弛豫现象可归因于晶体主体中的空间电荷效应,这种效应是由与电荷弛豫相关的有限时间尺度引起的,由于这些固体具有较大的静态介电常数和较低的电导率,因此会在这一频率范围内发生电荷弛豫。与 MAPI(电导率较低)相比,FAPI(电导率较高)中的电荷弛豫更快。照明产生的电子-空穴对通过降低势垒增强了电子传导性并加速了离子迁移;这反过来又缩短了电荷弛豫时间并增强了弛豫过程。根据照明导致的弛豫时间缩短推断,势垒的降低与载流子产生导致的化学势变化有关。
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引用次数: 0
Vortex penetration along twin boundaries in pristine and proton-irradiated FeSe 原始和质子辐照 FeSe 中沿孪生边界的涡流穿透
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-21 DOI: 10.1103/physrevmaterials.8.084806
Tong Ren, Yue Sun, Francesco Laviano, Ryousuke Sakagami, Zhi Xiang Shi, Tsuyoshi Tamegai
Below Ts90K, single-crystal FeSe undergoes a structural phase transition coinciding with the emergence of lattice domain boundaries, termed twin boundaries. Polarized-light microscopy validated the presence of twin boundaries in pristine FeSe and indicated the existence of extensive microsized twining in proton-irradiated FeSe. In twinned FeSe, vortex penetration displays a fractal, mazelike pattern, likely guided by these twin domains. We speculate substantial microtwinning in the proton-irradiation crystals, yet macroscopic twin boundaries persist as primary conduits for vortex motion.
在 Ts∼90K 温度以下,单晶硒化铁会发生结构相变,同时出现晶格畴界(称为孪晶界)。偏光显微镜验证了原始 FeSe 中孪晶边界的存在,并表明质子辐照 FeSe 中存在广泛的微小缠绕。在孪晶硒铁中,涡流穿透显示出一种分形的迷宫模式,很可能是由这些孪晶域引导的。我们推测质子辐照晶体中存在大量微孪晶,但宏观孪晶边界仍然是涡旋运动的主要通道。
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引用次数: 0
Differing vibrational properties of halide and chalcogenide perovskite semiconductors and impact on optoelectronic performance 卤化物和铬化包晶半导体的振动特性差异及其对光电性能的影响
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-08-20 DOI: 10.1103/physrevmaterials.8.085402
Kevin Ye, Matan Menahem, Tommaso Salzillo, Florian Knoop, Boyang Zhao, Shanyuan Niu, Olle Hellman, Jayakanth Ravichandran, R. Jaramillo, Omer Yaffe
We report a comparative study of temperature-dependent photoluminescence and structural dynamics of two perovskite semiconductors, the chalcogenide BaZrS3 and the halide CsPbBr3. These materials have similar crystal structures and direct band gaps, but we find that they have quite distinct optoelectronic and vibrational properties. Both materials exhibit thermally activated nonradiative recombination, but the nonradiative recombination rate in BaZrS3 is four orders of magnitude faster than in CsPbBr3, for the crystals studied here. Raman spectroscopy reveals that the effects of phonon anharmonicity are far more pronounced in CsPbBr3 than in BaZrS3. Further, although both materials feature a large dielectric response due to low-energy polar optical phonons, the phonons in CsPbBr3 are substantially lower in energy than in BaZrS3. Our results suggest that electron-phonon coupling in BaZrS3 is more effective at nonradiative recombination than in CsPbBr3 and that BaZrS3 may also have a substantially higher concentration of nonradiative recombination centers than CsPbBr3. The low defect concentration in CsPbBr3 may be related to the ease of lattice reconfiguration, typified by anharmonic bonding. It remains to be seen to what extent these differences are inherent to the chalcogenide and halide perovskites and to what extent they can be affected by materials processing.
我们报告了对两种包晶半导体--掺杂镓的 BaZrS3 和卤化物 CsPbBr3--随温度变化的光致发光和结构动力学的比较研究。这两种材料具有相似的晶体结构和直接带隙,但我们发现它们具有截然不同的光电和振动特性。这两种材料都表现出热激活非辐射重组,但就本文研究的晶体而言,BaZrS3 的非辐射重组速率比 CsPbBr3 快四个数量级。拉曼光谱显示,声子非谐波效应在 CsPbBr3 中要比在 BaZrS3 中明显得多。此外,尽管这两种材料都因低能极性光学声子而具有较大的介电响应,但 CsPbBr3 中的声子能量远远低于 BaZrS3。我们的研究结果表明,BaZrS3 中的电子-声子耦合比 CsPbBr3 中的非辐射重组更有效,而且 BaZrS3 中的非辐射重组中心浓度也可能比 CsPbBr3 中的高得多。CsPbBr3 中的低缺陷浓度可能与以非谐波键为典型代表的晶格重构容易有关。这些差异在多大程度上是钙钛矿和卤化物包晶所固有的,以及在多大程度上会受到材料加工的影响,还有待观察。
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引用次数: 0
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Physical Review Materials
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