Strain engineering provides an effective way of tailoring the electronic and optoelectronic properties of semiconductor nanomaterials and nanodevices, giving rise to novel functionalities. Here, we present direct experimental evidence of strain-induced modifications of hole mobility in individual GaAs nanowires, using in situ transmission electron microscopy (TEM). The conductivity of the nanowires varied with applied uniaxial tensile stress, showing an initial decrease of ~5-20% up to a stress of 1~ 2 GPa, subsequently increasing up to the elastic limit of the nanowires. This is attributed to a hole mobility variation due to changes in the valence band structure caused by stress and strain. The corresponding lattice strain in the nanowires was quantified by in situ 4D-scanning TEM (STEM) and showed a complex spatial distribution at all stress levels. Meanwhile, a significant red shift of the band gap induced by the stress and strain was unveiled by monochromated electron energy loss spectroscopy.
Understanding the Effect of Uniaxial Tensile Strain on the Early Stages of Sensitization in AISI 304 Austenitic Stainless Steel
在本研究中，已试图了解不同的竞争机制控制的整体程度的敏化（DOS）的变形奥氏体不锈钢在敏化的早期阶段的效果。进行了双回路电化学动电位再活化（DL-EPR）研究，以表征作为预定义的应变和敏化温度的函数的敏化度（DOS）。用X射线衍射（XRD）和扫描电子显微镜（SEM）定性地解释了这一现象。DOS随形变和敏化温度的变化呈现非单调性。形变诱发马氏体（DIM）的存在和它们在较高温度下转变成回火马氏体（α + Fe 3C）被发现在控制整体敏化和脱敏过程中起着重要作用。
In this work, we report on the mechanical responses and fracture behavior of pristine and defected monolayer 1T-Titanium Disulfide using classical molecular dynamics simulation. We investigated the effect of temperature, strain rate and defect ratio on the uniaxial tensile properties in both armchair and zigzag direction. We found that monolayer TiS2 shows isotropic uniaxial tensile properties except for failure strain which is greater in zigzag direction than armchair direction. We also observed a negative correlation of ultimate tensile strength, failure strain and young's modulus with tempe…
Nearly 30% increase of the ferromagnetic phase transition temperature has been achieved in strained MnAs nanocrystals embedded in a wurtzite GaAs matrix. Wurtzite GaAs exerts tensile stress on hexagonal MnAs nanocrystals, preventing a hexagonal to orthorhombic structural phase transition, which in the bulk MnAs is combined with the magnetic one. This effect results in a remarkable shift of the magneto-structural phase transition temperature from 313 K in the bulk MnAs to above 400 K in the tensely strained MnAs nanocrystals. This finding is corroborated by the state of the art transmission ele…
We present a novel machine learning based surrogate modeling method for predicting spatially resolved 3D microstructure evolution of polycrystalline materials under uniaxial tensile loading. Our approach is orders of magnitude faster than the existing crystal plasticity methods enabling the simulation of large volumes that would be otherwise computationally prohibitive. This work is a major step beyond existing ML-based modeling results, which have been limited to either 2D structures or only providing average, rather than local, predictions. We demonstrate the speed and accuracy of our surrog…
Strain manipulation of the magnetic domains, such as the stripe domains and skyrmions, has attracted considerable attention because of its potential applications for magnetic logic and memory devices. Here, utilizing phase-field modeling, we demonstrate the deterministic modulation of the orientation and the configuration of the stripe domains and skyrmions by using a uniaxial strain. The reorientation of the stripe domains can be caused by a suitable strain, and the direction of the reorientated domains is determined by the direction of the applied uniaxial strain and the type of domain walls…
High entropy alloys are finding significant scientific interest due to their exotic microstructures and exceptional properties resulting thereof. These alloys have excellent corrosion resistance and may find broad range of applications from bio-implants, aerospace components and nuclear industry. A critical performance metric that determines the application worthiness of the alloys is the resilience of stressed structural members in a corrosive environment. This study reports the results from a novel experimental setup to quantify the corrosion rate under uniaxial tensile stress in a single ph…
Using first-principles calculations we determine the role of compressive and tensile uniaxial and equibiaxial strain on the structural, electronic and magnetic properties of V$_2$O$_3$. We find that compressive strain increases the energy cost to transition from the high-temperature paramagnetic metallic phase to the low-temperature antiferromagnetic insulating phase. This shift in the energy difference can be explained by changes in the V-V bond lengths that are antiferromagnetically aligned in the low temperature structure. The insights that we have obtained provide a microscopic explanation…
Antiferromagnetic thin films typically exhibit a multi-domain state, and control of the antiferromagnetic Néel vector is challenging as antiferromagnetic materials are robust to magnetic perturbations. By relying on anisotropic in-plane strain engineering of epitaxial thin films of the prototypical antiferromagnetic material LaFeO3, uniaxial Néel vector control is demonstrated. Orthorhombic (011)- and (101)-oriented DyScO3, GdScO3 and NdGaO3 substrates are used to engineer different anisotropic in-plane strain states. The anisotropic in-plane strain stabilises structurally monodomain monoclini…
The Dirac nodal-line semimetals (DNLS) are new promising materials for technological applications due to its exotic properties, which originate from band structures dispersion and nodal-line behavior. We report a study on effects of several possibilities of strains in ZrSiSe DNLS on band structure dispersion and nodal-line behavior through the means of the density functional theory (DFT) calculations. We found that the Dirac nodal-line of ZrSiSe is robust to all strain with reasonable magnitude. Although, there are significant changes in gap, amplitude, and energy relative to Fermi energy. We …
Uniaxial tensile tests are performed on a polymethyl methacrylate (PMMA) grade over a range of temperatures near the glass transition and over two decades of strain rate. Deformation maps are constructed for Young's modulus, flow strength, and failure strain as a function of temperature for selected strain rates. The glassy, glass transition and rubbery regimes are identified, and constitutive relations are calibrated for the modulus and flow strength within each regime.
Decoupling the effects of geometry and nature of strain in LaMnO$_3$: Interplay of dynamic correlations and uniaxial strain driving magnetic phase transitions
Recently, Chi Xu et al. predicted the phase-filling singularities (PFS) in the optical dielectric function (ODF) of the highly doped $n$-type Ge and confirmed in experiment the PFS associated $E_{1}+Δ_{1}$ transition by advanced \textit{in situ} doping technology [Phys. Rev. Lett. 118, 267402 (2017)], but the strong overlap between $E_{1}$ and $E_{1}+Δ_{1}$ optical transitions made the PFS associated $E_{1}$ transition that occurs at the high doping concentration unobservable in their measurement. In this work, we investigate the PFS of the highly doped n-type Ge in the presence of the uniaxia…
Unusual anisotropic response of the charge carrier mobility to uniaxial mechanical strain in Rubrene crystals
本文系统地研究了Rubrene单晶在单轴机械应变下的电荷输运，在平行或垂直于电流方向的拉伸和压缩应变下，在晶体的两个面内输运方向上。陷阱态密度保持不变。场效应迁移率作为分子间输运的基准数据，发现随着压缩应变而增加，反之亦然，其幅度为-1.5 cm 2/Vs/ %应变，与输运方向无关。一个非常显著的结果是当晶体垂直于输运方向应变时迁移率的变化。虽然这种增强可以从改进的波函数重叠定量地解释，但垂直方向上的流动性提高得更多，这与基于后期扩展和通常的泊松比的简单几何考虑相反。这一结果强调了有机分子晶体中应力引起的动力学波函数重叠变化的中心作用。
Two-dimensional (2D) magnetoelectric multiferroics are promising multifunctional materials for miniaturized logic and memory devices. Herein, we explore the effectiveness of strain-engineering for tuning the properties of a recently predicted 2D antiferromagnetic-ferroelectric, VOCl2 monolayer. Interestingly, we find that magnetic-ordering and electric polarization can be tuned independently using uniaxial tensile strain along different in-plane lattice vectors. A 4% tensile strain along lattice vector b induces a transition from an antiferromagnetic (AFM) ground state with an out-of-plane mag…
Persistent spin textures are highly desirable for applications in spintronics as they may allow for long carrier spin lifetimes. However, they are also rare as only four point groups can host such textures, and even for these four groups, the emergence of persistent spin textures requires a delicate balance between coupling parameters, which control the strength of spin-momentum interactions. We use first-principles density functional simulations to predict the possibility of achieving these desirable spin textures through the application of uniaxial stress. Hybrid organic-inorganic perovskite…
We consider the case of a chiral soliton lattice subjected to uniaxial elastic strain applied perpendicular to the chiral axis and derive through analytical modelling the phase diagram of magnetic states supported in the presence of an external magnetic field. The strain induced anisotropies give rise to three distinct non-trivial spin textures, depending on the nature of the strain, and we show how these states may be identified by their signatures in Lorentz transmission electron microscopy (TEM). Experimental TEM measurements of the Fresnel contrast in a strained sample of the prototypical …
A metastable austenitic Fe-Cr-Ni steel was processed by selective laser melting with low power, resulting in nearly random crystallographic texture. In-situ tensile loading and neutron diffraction experiments were undertaken and the results indicate high ductility, despite the presence of porosity, and pronounced strain-induced martensitic transformation. A secondary hardening is observed in the mechanical data due to the martensite carrying significant load, upon its formation. The pronounced martensitic transformation is discussed with respect to the initial and the evolving deformation text…
Taper-free InP twinning superlattice (TSL) nanowires with an average twin spacing of ~ 13 nm were grown along the zinc-blende close-packed [111] direction using metalorganic vapor phase epitaxy. The mechanical properties and fracture mechanisms of individual InP TSL nanowires in tension were ascertained by means of in situ uniaxial tensile tests in a transmission electron microscope. The elastic modulus, failure strain and tensile strength along the [111] direction were determined. No evidence of inelastic deformation mechanisms was found before fracture, which took place in a brittle manner a…
Elastic and electronic tuning of magnetoresistance in MoTe$_2$
准二维过渡金属二硫属化物（TMD）具有显著的性质，可以改变电子和光子器件。我们报告了如何在MoTe $_2$，一种II型Weyl半金属，在高磁场下观察到的巨大的磁电阻（MR），可以在拉伸应变下可逆地控制。当沿$a$晶体学方向施加单轴应变时，在低温和高磁场下，MR增强多达~ 30%，并且当沿$b$方向施加应变时，MR减小大约相同的量。我们表明，大的面内电各向异性耦合的结构转变，从1 T '单斜的Td正交Weyl相。通过最小的拉伸应变实现Td -1 T '相界的移动。MR对拉伸应变的敏感性表明在Weyl点附近的电子和空穴袋的非平凡的自旋轨道纹理的可能性。我们的从头计算确实显示了一个显着的费米面上的轨道混合，这是修改的拉伸应变。
