arXiv: Materials Science最新文献_第10页

Topological Hall effect and magnetic states in the Nowotny chimney ladder compound Cr11Ge19 诺沃特尼烟囱阶梯化合物Cr11Ge19的拓扑霍尔效应和磁态

arXiv: Materials Science Pub Date : 2020-10-12 DOI: 10.1103/PHYSREVB.103.024445

Yu Li, X. Gui, Mojammel A. Khan, W. Xie, D. Young, J. Ditusa

{"title":"Topological Hall effect and magnetic states in the Nowotny chimney ladder compound \u0000Cr11Ge19","authors":"Yu Li, X. Gui, Mojammel A. Khan, W. Xie, D. Young, J. Ditusa","doi":"10.1103/PHYSREVB.103.024445","DOIUrl":"https://doi.org/10.1103/PHYSREVB.103.024445","url":null,"abstract":"We have investigated the magnetic and charge transport properties of single crystals of Nowotney Chimney Ladder compound Cr$_{11}$Ge$_{19}$ and mapped out a comprehensive phase diagram reflecting the complicated interplay between the Dzyaloshinskii-Moriya (DM) interaction, the dipolar interaction, and the magnetic anisotropy. We have identified a set of interesting magnetic phases and attributed a finite topological Hall effect to the recently discovered bi-skyrmion phase. These data also suggest the existence of an anti-skyrmion state at finite fields for temperatures just below the magnetic ordering temperature, $T_c$, as indicated by a distinct change in sign of the topological Hall effect. Above $T_c$, we discovered a region of enhanced magnetic response corresponding to a disordered phase likely existing near the ferromagnetic critical point under small magnetic fields. Strong spin chirality fluctuations are demonstrated by the large value of the topological Hall resistivity persisting up to 1 T which is most likely due to the existence of the DM interaction. We argue that changes to the topological Hall effect correspond to different topological spin textures that are controlled by magnetic dipolar and DM interactions that vary in importance with temperature.","PeriodicalId":8467,"journal":{"name":"arXiv: Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76404336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Origins of the transformability of nickel-titanium shape memory alloys 镍钛形状记忆合金可变形性的起源

arXiv: Materials Science Pub Date : 2020-10-11 DOI: 10.1103/physrevmaterials.4.103611

Xian Chen, C. Ophus, C. Song, J. Ciston, Sambit Das, Yintao Song, Y. Chumlyakov, A. Minor, V. Gavini, R. James

引用次数: 2

Crystal truncation rods from miscut surfaces with alternating terminations 晶体截断棒从错误切割的表面与交替的终止

arXiv: Materials Science Pub Date : 2020-10-11 DOI: 10.1103/PHYSREVB.103.125402

Guangxu Ju, Dongwei Xu, C. Thompson, M. Highland, J. Eastman, W. Walkosz, P. Zapol, G. Stephenson

引用次数: 2

Concurrence of ferroelectric, dielectric and magnetic behaviour in Tb2Ti2O7 pyrochlore Tb2Ti2O7焦绿石的铁电、介电和磁性同时行为

arXiv: Materials Science Pub Date : 2020-10-10 DOI: 10.1016/j.physleta.2020.127085

B. Santhosh Kumar, Rajesh Narayana Perumal, C. Venkateswaran

引用次数: 6

Ferroelectricity and ferromagnetism in a VOI2 monolayer: Role of the Dzyaloshinskii-Moriya interaction VOI2单层中的铁电性和铁磁性:Dzyaloshinskii-Moriya相互作用的作用

arXiv: Materials Science Pub Date : 2020-10-10 DOI: 10.1103/PhysRevB.102.165129

N. Ding, Jun Chen, S. Dong, A. Stroppa

{"title":"Ferroelectricity and ferromagnetism in a \u0000VOI2\u0000 monolayer: Role of the Dzyaloshinskii-Moriya interaction","authors":"N. Ding, Jun Chen, S. Dong, A. Stroppa","doi":"10.1103/PhysRevB.102.165129","DOIUrl":"https://doi.org/10.1103/PhysRevB.102.165129","url":null,"abstract":"Multiferroics with intrinsic ferromagnetism and ferroelectricity are highly desired but rather rare, while most ferroelectric magnets are antiferromagnetic. A recent theoretical work [Phys. Rev. B {bf 99}, 195434 (2019)] predicted that oxyhalides VO$X_2$ ($X$: halogen) monolayers are two-dimensional multiferroics by violating the empirical $d^0$ rule. Most interestingly, the member VOI$_2$ are predicted to exhibit spontaneous ferromagnetism and ferroelectricity. In this work, we extend the previous study on the structure and magnetism of VOI$_2$ monolayer by using density functional theory and Monte Carlo simulation. The presence of the heavy element iodine with a strong spin-orbit coupling leads an effective Dzyaloshinskii-Moriya interaction in the polar structure, which favors a short-period spiral a magnetic structure.. Another interesting result is that the on-site Coulomb interaction can strongly suppress the polar distortion thus leading to a ferromagnetic metallic state. Therefore, the VOI2 monolayer is either a ferroelectric insulator with spiral magnetism or a ferromagnetic metal, instead of a ferromagnetic ferroelectric system. Our study highlights the key physical role of the Dzyaloshinskii-Moriya interaction.","PeriodicalId":8467,"journal":{"name":"arXiv: Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80325454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 18

Ferroelastic Hysteresis in Thin Films of Methylammonium Lead Iodide. 碘化铅甲基铵薄膜的铁弹性迟滞。

arXiv: Materials Science Pub Date : 2020-10-10 DOI: 10.1021/acs.chemmater.0c03776.s001

R. Kennard, Clayton J. Dahlman, R. DeCrescent, J. Schuller, K. Mukherjee, R. Seshadri, M. Chabinyc

{"title":"Ferroelastic Hysteresis in Thin Films of Methylammonium Lead Iodide.","authors":"R. Kennard, Clayton J. Dahlman, R. DeCrescent, J. Schuller, K. Mukherjee, R. Seshadri, M. Chabinyc","doi":"10.1021/acs.chemmater.0c03776.s001","DOIUrl":"https://doi.org/10.1021/acs.chemmater.0c03776.s001","url":null,"abstract":"Mechanical strain can modify the structural and electronic properties of methylammonium lead iodide MAPbI3. The consequences of ferroelastic hysteresis, which involves the retention of structural memory upon cycles of deformation, in polycrystalline thin films of MAPbI3 are reported. Repeatedly bent films of MAPbI3 on flexible polyimide substrates were examined using Grazing Incidence Wide-Angle X-ray Scattering (GIWAXS) to quantitatively characterize the strain state, populations, and minimum sizes of twin domains. Approximate locations for the coercive stress and saturation on the ferroelastic stress-strain curve are identified, and domains from differently-strained twin sets in the films are found to interact with each other. The presence of specific twin domains is found to correlate to reports of the heterogeneity of strain states with defect content. Long-term stability testing reveals that domain walls are highly immobile over extended periods. Nucleation of new domain walls occurs for specific mechanical strains and correlates closely with degradation of the films. These results help to explain the behavior of ion migration, degradation rate, and photoluminescence in thin films under compressive and tensile strain.","PeriodicalId":8467,"journal":{"name":"arXiv: Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80378342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Understanding Cu incorporation in the Cu2xHg2−xGeTe4 structure using resonant x-ray diffraction 用共振x射线衍射了解Cu在Cu2xHg2−xGeTe4结构中的掺入

arXiv: Materials Science Pub Date : 2020-10-09 DOI: 10.1103/PHYSREVMATERIALS.5.015402

Ben L. Levy-Wendt, B. Ortiz, L. C. Gomes, K. Stone, D. Passarello, E. Ertekin, E. Toberer, M. Toney

{"title":"Understanding Cu incorporation in the \u0000Cu2xHg2−xGeTe4\u0000 structure using resonant x-ray diffraction","authors":"Ben L. Levy-Wendt, B. Ortiz, L. C. Gomes, K. Stone, D. Passarello, E. Ertekin, E. Toberer, M. Toney","doi":"10.1103/PHYSREVMATERIALS.5.015402","DOIUrl":"https://doi.org/10.1103/PHYSREVMATERIALS.5.015402","url":null,"abstract":"The ability to control carrier concentration based on the extent of Cu solubility in the $mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ alloy compound (where 0 $leq$ x $leq$ 1) makes $mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ an interesting case study in the field of thermoelectrics. While Cu clearly plays a role in this process, it is unknown exactly how Cu incorporates into the $mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ crystal structure and how this affects the carrier concentration. In this work, we use a combination of resonant energy X-ray diffraction (REXD) experiments and density functional theory (DFT) calculations to elucidate the nature of Cu incorporation into the $mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ structure. REXD across the $mathrm{Cu_k}$ edge facilitates the characterization of Cu incorporation in the $mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ alloy and enables direct quantification of anti-site defects. We find that Cu substitutes for Hg at a 2:1 ratio, wherein Cu annihilates a vacancy and swaps with a Hg atom. DFT calculations confirm this result and further reveal that the incorporation of Cu occurs preferentially on one of the z = 1/4 or z = 3/4 planes before filling the other plane. Furthermore, the amount of $mathrm{Cu_{Hg}}$ anti-site defects quantified by REXD was found to be directly proportional to the experimentally measured hole concentration, indicating that the $mathrm{Cu_{Hg}}$ defects are the driving force for tuning carrier concentration in the $mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ alloy. The link uncovered here between crystal structure, or more specifically anti-site defects, and carrier concentration can be extended to similar cation-disordered material systems and will aid the development of improved thermoelectric and other functional materials through defect engineering.","PeriodicalId":8467,"journal":{"name":"arXiv: Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87761125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Skew scattering and side jump of spin wave across magnetic texture 磁结构中自旋波的斜散射和侧跳

arXiv: Materials Science Pub Date : 2020-10-09 DOI: 10.1103/PHYSREVB.103.054428

Jin Lan, Jiang Xiao

引用次数: 11

The effect of ion irradiation on dephasing of coherent optical phonons in GaP 离子辐照对GaP中相干光学声子消相的影响

arXiv: Materials Science Pub Date : 2020-10-08 DOI: 10.1063/5.0020810

Takuto Ichikawa, Y. Saito, M. Hase

引用次数: 0

Vacancy defects induced changes in the electronic and optical properties of NiO studied by spectroscopic ellipsometry and first-principles calculations 利用椭圆偏振光谱和第一性原理计算研究了空位缺陷引起的NiO电子和光学性质的变化

arXiv: Materials Science Pub Date : 2020-10-07 DOI: 10.1063/5.0021650

K. Egbo, C. Liu, C. Ekuma, K. Yu

{"title":"Vacancy defects induced changes in the electronic and optical properties of NiO studied by spectroscopic ellipsometry and first-principles calculations","authors":"K. Egbo, C. Liu, C. Ekuma, K. Yu","doi":"10.1063/5.0021650","DOIUrl":"https://doi.org/10.1063/5.0021650","url":null,"abstract":"Native defects in semiconductors play an important role in their optoelectronic properties. Nickel oxide (NiO) is one of the few wide-gap p-type oxide semiconductors and its conductivity is believed to be controlled primarily by Ni-vacancy acceptors. Herein, we present a systematic study comparing the optoelectronic properties of stoichiometric NiO, oxygen-rich NiO with Ni vacancies (NiO:VNi), and Ni-rich NiO with O vacancies (NiO:VO). The optical properties were obtained by spectroscopic ellipsometry, while valence band spectra were probed by high-resolution x-ray photoelectron spectroscopy. The experimental results are directly compared to first-principles density functional theory + U calculations. Computational results confirm that gap states are present in both NiO systems with vacancies. Gap states in NiO:Vo are predominantly Ni 3d states, while those in NiO:VNi are composed of both Ni 3d and O 2p states. The absorption spectra of the NiO:VNi sample show significant defect-induced features below 3.0 eV compared to NiO and NiO:VO samples. The increase in sub-gap absorptions in NiO:VNi can be attributed to gap states observed in the electronic density of states. The relation between native vacancy defects and electronic and optical properties of NiO are demonstrated, showing that at similar vacancy concentration, the optical constants of NiO:VNi deviate significantly from those of NiO:VO. Our experimental and computational results reveal that although VNi are effective acceptors in NiO, they also degrade the visible transparency of the material. Hence, for transparent optoelectronic device applications, an optimization of native VNi defects with extrinsic doping is required to simultaneously enhance p-type conductivity and transparency.","PeriodicalId":8467,"journal":{"name":"arXiv: Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79107371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 34