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In this present study, a Friction stir weld (FSW) technique is applied to fabricate the FSW joints of aluminium alloy plates of 2024-T351 and 7075-T651 in butt-joint arrangement using a FSW tool of shape taper threaded cylindrical (TTC). The FSW joints are produced using constant FSW parameters of tool rotation speed (TRS) of 650 rpm, tool traverse speed (TTS) of 150 mm/min and tool plunge depth (TPD) of 6.20 mm. Tensile and microstructure specimens are removed from the weld joint in the direction perpendicular to the tool traverse and across the weld region. Initially, each of these specimens are heat treated to solution temperature (400, 420, 440, 460, 480, 500 °C) for 1 h and tested for tensile properties. The heat-treated microstructure samples are examined for the presence of abnormal grain growth (AGG) in the weld nugget zone (WNZ), thermally affected zone (TMAZ), heat affected zone (HAZ) of the weld region using stereo-zoom microscope and scanning electron microscope (SEM). Microstructure specimens subjected to solution heat treatment up to 480 °C are stable and reveals no AGG. However, for 500 °C the microstructures are not stable and the presence of AGG in the weld regions are observed. At 480 °C, the tested specimen shows homogeneity in hardness distribution across the weld regions. Thus, solution temperature of 480 °C is chosen as an optimizing solution temperature. Further, the tensile specimens are subjected to ageing temperature with constant temperature of 180 °C for various durations range 5, 8 and 12 h. Thus, these experimental investigations indicate that the specimen subjected to solution treatment at 480 °C followed by ageing temperature of 180 °C for 12 h show higher ultimate tensile strength (UTS) of 435 MPa and percentage increase of 6.8% compared to the specimens without heat treatment having UTS of 407 MPa.

The electrochemical growth of Heusler alloy film with good morphological quality and crystalline order using single-crystalline substrate is demonstrated. Static magneto optical Kerr effect studies are employed to reveal the surface magnetization reversal of the films. An understanding of the intrinsic nature of the magnetization dynamics in this class of electrochemically grown materials is presented using time-resolved magneto optical Kerr effect measurements, under femtosecond laser excitation. Excitation laser fluence dependence study reveals the ultrafast demagnetization time, fast remagnetization time, and magnetic damping parameter as well as their correlation. © 2021 American Chemical Society. All rights reserved.

Copper oxide nanoparticles were successfully prepared by a simple solution combustion technique with cupric nitrate and glycine solutions. The formation of copper oxide nanoparticles was confirmed by UV-visible spectroscopy and X-ray diffraction. The surface structure of nanoparticles was obtained by scanning electron microscopy. UV-visible absorption spectroscopy and X-ray diffraction confirm the existence of mixed-phase copper oxide nanoparticles. The standard agar well diffusion technique has been adopted to evaluate the antimicrobial activity of nanoparticles and found suitable for antimicrobial applications. The nonlinear optical activity of the copper oxide nanoparticles was studied using Z-scanning with a continuous-wave laser at 532 nm wavelength. The experimental result suggests that the prominent nonlinear absorption in the nanoparticles having a nonlinear absorption coefficient of 7.14 × 10-2 cm/W. Nanoparticles display superior optical limitation due to strong nonlinear absorption in the nanoparticles which may be attributed to interband and intraband transitions.

An energy harvesting system which concentrates heat from a automobile fumes channel and transforms the warmth into power by utilizing thermoelectric power generators (TEGs) has been built. Thermoelectric modules are additionally utilized in the collect of waste warmth in wood ovens, heater dividers, and mechanical stacks. In Bioengineering, there are applications for little scope age including the utilization of warmth from the human body to take care of microelectronic gadgets and self-sufficient sensors. In this paper, examination of waste warmth changes over into electrical energy through thermo electric generators has been completed. The thermo electric generator module is associated inner burning motor fumes heat exchanger to conceivable exchange of warmth. The temperature distinction among hot and cold surface has been kept up from 10 °C to 80 °C. The resultant estimation of output voltage and power are acquired through thermo electric generators.

Aim and Objective: Was to assess and compare the microleakage of G-aenial Universal Flo, Smart Dentin Replacement and Tetric Evo Ceram bulk fill resin composites in class V cavities along the occlusal and gingival margins using dye penetration test under stereomicroscope. Materials and Methods: Seventy five human extracted premolars were selected and randomly divided into 3 groups (n=25), as per the restorative materials for microleakage test. Group I: Tetric Evo Ceram (Bulk fill non flowable). Group II: G-aenial Universal Flo (Highly filled flowable resin composite). Group III: Smart Dentin Replacement (Bulk fill flowable resin composite). Class V (box) cavities were prepared both on the buccal and lingual surfaces of each of the 75 teeth, a total of 150 cavities, restored, immersed in 2% methylene blue dye for 24 hours and then sectioned bucco lingually into two halves. Dye penetration score was measured along occlusal and gingival wall using a Stereomicroscope at 40X magnification. Statistical analysis was done using Chi square test for microleakage assessment. P value was set at E‚0.05. Result: Intergroup comparison showed statistically no significant difference between the three groups both occlusal and gingival wall, whereas groupwise comparison showed statistically significant result between group I and Group II at gingival wall with P value 0.021. Conclusion: None of three resin composite materials were free from microleakage. All the three materials showed more microleakage at gingival wall compared to occlusal wall. Among all the tested groups G-aenial Universal Flo showed the least microleakage at the gingival wall. Keyword: Microleakage, Class V, Resin composites.

Analysis of Barkhausen avalanches in thin films of magnetic material has been an active area of research due to the proximity of the dimensionality crossover. However, the measurement of avalanches in ultrathin films (thickness and . The observations could not be explained within the framework of the established front propagation or nucleation models under adiabatic evolution. We attempt to explain our findings by performing simulations of the 2D random field Ising model under non-adiabatic evolution with a constant field step, and obtain good qualitative agreement between experimental and simulated probability distributions for high disorder levels. We conclude that the observed peculiarities are a consequence of strong pinning and the departure from the adiabatic condition during magnetic field sweep.

Friction stir processing (FSP) is a new technique to produce fine-grained microstructure with enhanced microstructure characteristics and mechanical properties compared to the base metal (BM). However, microstructures are not stable under elevated temperature. The microstructure of the friction stir processed (FSPed) metallic substrate can be improved by reinforcing the matrix with secondary phase particles. With this motivation, aluminium alloy plate of typically AA7075-T651 is reinforced with nano-particles of silicon carbide (SiCNP) and the composites were processed by FSP at the tool-rotation speed (TRS) of 1000 rpm and the tool-traverse speed (TTS) of 25 mm/min with six passes. The grain stability of the composite was studied by heat-treating to temperatures range 450 °C–500 °C for various durations range 1 h 30 min to 4 h 30 min. Micro and macrostructure of heat-treated samples are characterized using an scanning electron microscopy (SEM) and optical microscope (OM). Results showed that even after 4 h 30 min of samples subjected to heat treatment, the grains structures of the FSPed composites were stable at 450 °C. Further, for higher temperatures, i.e. 475 °C and 500 °C, composite grain structures at the stir zone (SZ) were stable up to 3 h. In comparison, abnormal grain growth (AGG) was observed in the six-pass FSPed aluminium alloy plate of AA7075-T651 without addition of SiCNP and heat-treated for 450 °C for 1 h 30 min. Thus, these experimental investigations indicate that grain boundary pinning by SiCNP has significantly increased the stability of the grains under elevated temperature and results in grain refinement with average grain size range 1.5–2 µm at the SZ of the FSPed composites.

Kerr microscopy measurements of Ta/Pt/CoFeB/Pt thin films, with ferromagnetic (FM) CoFeB layer grown by oblique-angle sputter deposition, indicated a quasi-perpendicular magnetic anisotropy. In such a system, the anisotropy is slightly tilted from the normal to substrate plane. The effect of tilt was observed as shift in out-of-plane (OP) room-temperature hysteresis, in presence of in-plane (IP) bias field. Tilt angles were obtained by measuring the shifts in OP hysteresis for several magnitudes and relative azimuthal orientations of bias field with respect to IP projection of tilted anisotropy direction. We studied variation of tilt angle as function of FM layer thickness which was increased near to Spin Reorientation Transition (SRT) value for FM layer in corresponding system. We also studied this variation for different bottom Pt layer thicknesses. The results of our experiment show the variation to follow two different profiles − one monotonic and the other non-monotonic.

In the present work, a systematic investigation of electrical transport mechanism has been used as a tool to investigate the charge-order suppression and its crossover in Pr 0.5 Ca 0.5 MnO 3 (PCMO) manganite system with varying particle size and applied magnetic field. The samples with different particle sizes were synthesized by adopting sol-gel method and sintering at different temperatures. The prepared samples were thoroughly characterized by various physicochemical techniques. The activation energy and density of states at Fermi level obtained from the temperature-dependent electrical resistivity data clearly show the charge order crossover signatures and its suppression in the samples below 70 nm particle size and applied magnetic fields above 4 T. The significant change in various electrical transport parameters with the particle size around 70 nm could be attributed to the melting of long-range charge ordering behavior due to surface spin disorder and induced lattice-strain effects in PCMO manganite system.

We report the crossover of Barkhausen noise statistics upon a change in the measurement geometry. The behaviour is akin to the angle dependent critical to sub-critical crossover of avalanche statistics as present in avalanche models with random anisotropy directions. The samples studied were 15-25 nm thin films of iron, grown on (001) GaAs by pulsed laser ablation. Use of planar Hall effect as a probe for the magnetic state facilitated this work, which would be impractical to do in a MOKE setup. We compare our data with simulations of a random anisotropy Ising model, and demonstrate striking similarity between experimental and simulated avalanche size distributions. Further, through micromagnetic simulations, we conclude that crystallite misorientations were the origin of domain wall pinning in our system leading to Barkhausen noise.

POSS-general purpose elastomers are the least explored area in the field of POSS/polymer nanocomposites. Of the many general-purpose elastomers available, POSS nanocomposites with natural rubber (NR) and styrene butadiene rubber (SBR) have been mainly studied so far. Finding an ideal POSS filler suitable for rubber chain reinforcement is the main challenge here. Octavinyl POSS is the main filler used for NR composites, while octamethacryl POSS is used in SBR composites. General composite preparation methods and various properties of POSS-rubber composites in terms of various characterization techniques are described in detail in this chapter. The challenges in this field and key points for further research are also included.

Due to various architectural requirements the structures are subjected to large shear stresses and hence the study of shear performance of structural materials is essential. Push-off test is a simple test which can be performed to determine the in-plane shear strength (IPSS) of materials effectively. Geopolymer concrete is a recent construction material which is a suitable alternative cement concretes especially in precast construction due to the non-requirement of cement, the manufacture of which is energy intensive and involves the liberation of CO2 which is a known pollutant and leads to global warming. Concrete has good performance under compressive loads and fails generally due to crack propagation, bridging of these cracks can improve the load carrying capacity of the concrete, addition of fibre is one such method available where the fibres act as crack arrestors. The present experimental investigation has made an effort to understand the influence of fibres over shear strength of Geo Polymer Concrete (GPC) adopting push-off specimen. From the experimental studies it was observed that shear strength and resistance against cracking increased with increase in fibre volume and the effectiveness of GPC reinforced by fibres were higher than that of NSC specimen.Due to various architectural requirements the structures are subjected to large shear stresses and hence the study of shear performance of structural materials is essential. Push-off test is a simple test which can be performed to determine the in-plane shear strength (IPSS) of materials effectively. Geopolymer concrete is a recent construction material which is a suitable alternative cement concretes especially in precast construction due to the non-requirement of cement, the manufacture of which is energy intensive and involves the liberation of CO2 which is a known pollutant and leads to global warming. Concrete has good performance under compressive loads and fails generally due to crack propagation, bridging of these cracks can improve the load carrying capacity of the concrete, addition of fibre is one such method available where the fibres act as crack arrestors. The present experimental investigation has made an effort to understand the influence of fibres over shear strength of Geo Polymer Concre...

Polycrystalline Bi1-xHoxFe1-yZryO3 series has been synthesized by sol-gel method. The effect of Ho, Zr co- substitution on structure and magnetic properties were investigated. The results of the XRD patterns suggest that all the samples have a rhombohedral structure (space group R3c). The lattice parameters increase as the Ho, Zr concentration increases. Raman spectroscopy show vibration modes for all the samples associated with R3c phase accompanying a shift in the modes due to co-substitution of Ho and Zr. As Ho, Zr doping level increases, the weak ferromagnetism becomes more obvious with the effect that the saturation magnetization and coercivity gradually increases and attain maxima at x = y = 0.2.

Elongated holes are found in many aerospace structural components and are prone to fatigue failure due to the stress concentration effect at the edge of the hole. Different approaches like shape reworking, shape optimization, and cold expansion combined with interference fitting are currently used as a repair/life extension option, to overcome fatigue cracking problems around elongated holes. In practice, these approaches lead to either addition of material or modification of geometry. A novel and economical method derived from renowned hole cold expansion process is proposed in the literature to enhance the fatigue life of elongated hole without adding material and modifying hole geometries. Benefit of implementing proposed novel cold expansion method for elongated hole is investigated in this work through a simplified three-dimensional nonlinear Finite Element simulation. Distributions of induced beneficial residual stress around and along the thickness direction of elongated hole are predicted from the FE simulation. The results indicate introduction of significant beneficial residual stresses throughout the thickness surface of elongated hole. These beneficial residual stresses are responsible for fatigue life extension and can be further used to quantify the achieved fatigue life enhancement.

ErFe0.55Mn0.45O3 single crystal shows canted antiferromagnetic ordering below 365 K with weak ferromagnetic moment along c axis. On cooling, the magnetic moment is completely suppressed at a certain temperature due to Er and Fe/Mn sublattice compensation, below which negative magnetization is observed. The compensation and negative magnetization temperatures are much higher than those in other orthoferrite systems. There is a spin reorientation transition from Γ 4 ( G x , A y , F z ) to Γ 1 ( A x , G y , C z ) structure at 255 K along c axis which is not seen along a and b axes. The spin reorientation is tunable with applied magnetic field and is completely suppressed at sufficiently high magnetic field. The behavior is explained by spin configuration and net magnetization orientation of individual Er and Fe/Mn sublattices. The proposed model is further validated by measurements using ’training’ protocol.

SrIrO3 (SIO) is one of the materials known to exhibit a high spin-orbit coupling with correlated semi-metallic ground state, along with the topological states, as proven in recent times. In this regard, the SIO thin films grown by us on SrTiO3 (001) at certain deposition conditions, exhibit a low temperature magneto-transport behavior which is analogous to the materials with topological states. Further, we have explored various deposition conditions of SIO such as partial pressure of O2 and different temperatures of growth for different thickness of SIO. In addition, from the electrical transport properties, SIO thin films found to exhibit semi-metallic nature with either insulating-like or a crossover from metal-like to insulating-like behavior based on the conditions chosen for the growth. Moreover, the magneto-transport data of various SIO thin films are found to be obeying the usual B2 (Lorentzian) behavior in majority of the cases. At the same time, we have also observed the weak-localization and weak-antilocalization effects; along with a linear magneto-resistance at low temperature ranges. Thus, from our extensive measurements, it becomes clear that SIO thin films can exhibit wide varieties of magneto-transport properties based on the deposition conditions. Plethora of interesting properties exhibited by the highly spin-orbit coupled SIO epitaxial thin films at lower temperatures in the presence of magnetic field makes the material to be promising for the future applications in the field of spintronics.

The magnetic interaction between BiFeO 3 and SrRuO 3 layers in a heterostructure grown on (0 0 1) oriented SrTiO 3 substrate is investigated. A two-step magnetization reversal was observed in M−H hysteresis loop measurement of the heterostructure at 10 K. The first step in the hysteresis loop is associated with the switching of the free SrRuO 3 moments whereas the second step arises from the switching of the pinned moments. The total amount of the pinned SrRuO 3 moment was observed to decrease with increasing thickness of the BiFeO 3 layer. The presence of exchange bias effect in the heterostructure was confirmed by the field cooled M−H measurements where only the second step of hysteresis loop was observed to shift along the field axis. The coercivity of the second step of hysteresis loop decreases with increasing temperature and merges with that of the first step above 100 K which infers the desertion of the pinned magnetic moments. Temperature dependent capacitance measurement shows a kink at the ferromagnetic transition temperature of SrRuO 3 and a pronounced dip was observed in the second derivative of capacitance with respect to temperature, indicating a strong magneto-electric coupling between the two layers.

Single phase polycrystalline LuFe 1− x Ni x O 3 ( x = 0 − 0.3) (LFNO) nanoparticles are synthesized using the sol-gel method. X-ray diffraction measurements revealed that the crystal structure of Ni-doped samples is isomorphic to hexagonal LuFeO 3 (LFO). The phase pure hexagonal P6 3 cm symmetry exists for 0 ≤ x ≤ 0.3, and the secondary phases appear for x ≥ 0.4. Raman spectra show a shift in the mode frequency corresponding to the changes in Lu-O and Fe-O bond lengths with Ni doping. An enhancement in the magnetization is observed for LFNO throughout the temperature range (400–5 K) compared to LFO. The antiferromagnetic state of LFO becomes ferrimagnetic at low temperatures, and a net magnetization is observed at room temperature with Ni doping. As Ni concentration increases, a systematic increment in the ferroelectric polarization is observed. This enhancement in polarization is believed to be due to the distortion in FeO 5 cage, while the improvement in magnetic properties is due to the induced magnetic interactions, caused by the Fe-Ni interactions on the triangular lattice with Ni doping in LuFeO 3 .

NdxSr1−xMnO3 (0.2 ≤ x ≤ 0.5) systems are widely studied in magnetism, popular for high colossal magnetoresistance and are ferromagnetic oxides with TC ranging from 200 K to 300 K. Recently, many of such compounds are re-visited for exploring the correlation of spin, charge and lattice degrees of freedom. Although, manganite thin films are the ideal candidates for studying the electron-correlation effects, the puzzle of obtaining a high quality epitaxial thin films of NdxSr1−xMnO3 are still unsolved contrary to its sister compound LaxSr1−xMnO3. Hence, in this study, we demonstrate the growth of best quality of Nd0.6Sr0.4MnO3 (NSMO) epitaxial thin films. This is evident from the TC and a sharp insulator-to-metal transition (IMT) coinciding at as high as ∼255 K against the bulk TC (∼270 K). It is the highest reported TC in Nd0.6Sr0.4MnO3 thin films to date. Moreover, as-deposited films with in situ oxygen annealing are not enough to relax the lattice of NSMO films due to the significant Jahn-Teller distortion in the film. With ex situ annealing processes alongside the various deposition and in situ annealing conditions, we have extensively studied the growth of epitaxial NSMO thin films on LaAlO3 (0 0 1) and SrTiO3 (0 0 1) to investigate the evolution of lattice and its one-to-one correspondence with the magnetism and the electrical properties of thin films. Accordingly, the enhanced magnetization, reduced resistivity and the higher TC and IMT of the NSMO films obtained from our extensive growth analysis looks promising for the future applications across the TC and IMT.

We study the evolution of the magnetic field-induced switching between the stable domain configurations of permalloy nanoring structures, when magnetic nano-wires are attached to them. Magnetoresistance measurements were performed on such devices for two configurations of the attached nano-wires: (i) when they are at diametrically opposite ends of the nanoring, and (ii) when the nanowires are at an obtuse angle with respect to each other. During the measurements, the direction of application of the in-plane magnetic field is varied to understand the switching properties of the devices. Micromagnetic simulations were carried out in order to understand the domain configuration and reversal mechanism. We show that due to the nature of domain walls created by the presence of the nano-wires in the obtuse configuration, a vortex state can be stabilized in the nano-ring. We extended our studies to various nanoring devices with different widths while keeping a constant thickness.

Despite numerous attempts of electron doping in different manganites (RMnO3, R = rare earth), successful reports are scarce in the literature till date. In this paper, we have synthesized a series of phase-pure electron doped multiferroic compound Sc1-xZrxMnO3 (x = 0, 0.05, 0.1, and 0.2) and evaluated the effect of doping on structural properties, oxidation states of cations, DC magnetization, heat capacity, resistivity, dielectric behaviour and ferroelectricity in the material. The presence of Zr4+ and mixed valence state of Mn comprising of Mn2+ and Mn3+ ions are confirmed using X-ray photoelectron spectroscopy. All these samples exhibit antiferromagnetic ordering; as Zr4+ content increases, antiferromagnetic ordering gradually diminishes while shifting to low temperatures. Additionally, ferromagnetic-like interaction develops in doped systems which gives rise to hysteresis in isothermal magnetization loops with greatly enhanced magnetization in comparison to pure antiferromagnetic nature of x = 0 i.e. ScMnO3. Interestingly, even with zero magnetic moment of Sc3+, Schottky-like anomaly is observed at 5 K in heat capacity data of samples with x = 0.1 and 0.2, a result that we attribute to the highly resistive nature of doped samples. Moreover, while measuring ferroelectric hysteresis loops, we observe a significant reduction of leakage current in doped sample (x = 0.2) compared to pure ScMnO3. Additionally, the compound x = 0.2 shows improved dielectric and ferroelectric behaviour. It is proposed that doping of Zr4+ compensates for the cation deficiency and consequently eliminates the inherent oxygen vacancies by charge compensation. (C) 2017 Elsevier B.V. All rights reserved.

Solar Air Heater is a simple, cheap and most widely used for various applications such as textile industries, agricultural, desalination and space heating. Generally collectors are tilted so as to absorb maximum radiation, so it is necessary to calculate the optimum tilt angle to maximize the solar radiation falling on the collector area to gain maximum useful energy. The maximum solar radiation can be collected by using a tracking mechanism. Tracking systems are expensive and complicated in construction. The working operation of solar integrated tracking system is difficult. This paper presents the mechanism of evaluating the overall heat transfer coefficient of the solar air-heater at variable intensities and inlet velocities. The experimental setup is integrated with blower at inlet to the solar air heater in order to pump air at different velocities. The work focus on comparative study of solar air heating system for different tilt angles ranging from 250 to 600 and determines the overall heat transfer coefficient so as to find the optimum tilt angle of a solar flat plate collector.

Presence of a neighboring hole introduces limits on the level of expansion that can be applied during cold expansion of adjacent holes. Particularly in case of closely spaced holes, it is required to consider the effect of proximity hole in arriving at optimum cold expansion level. The present work is aimed at assessing the effect of neighboring hole on induced residual stresses during cold expansion of adjacent holes through finite element simulation. Four different situations of cold expansion of adjacent holes including a proposed novel approach are considered to obtain detailed insight into the extent of residual stresses induced. The proposed novel approach suggests insertion of a rigid pin into the neighboring hole during cold expansion. This effect has been incorporated during simulation of cold expansion. The simulation results show higher values of residual stresses induced and consequently, larger fatigue life enhancement benefits are expected through the proposed novel approach.

Objective: Two simple and sensitive techniques - one spectrophotometric and one titrimetric- have been developed for the determination of 3,3'-(propane-1,3-diyl)bis(7,8-dimethoxy-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one) commonly known as ivabradine impurity-9 (IVA-9). Methods: The spectrophotometric method is based on the oxidation of drug impurity by excess cerium (IV) sulphate in acidic medium and the subsequent reaction of the remaining Ce(IV) with a known amount of ferrous ammonium sulphate. The resultant ferric ion is then made to react with thiocyanate in acid medium to form a brown coloured complex which is analyzed spectrophotometrically against the reagent blank. In the volumetric method, the un-reacted Ce(IV) is titrated against standard ferrous ammonium sulphate to estimate the quantity of IVA-9. Results: The colored complex showed an absorption maximum at 479 nm when measured spectrophotometrically. The stated methods are validated statistically using the International Council for Harmonization guidelines-ICH Q2(R1) for precision and accuracy. The method showed a linear response from 0.5 to 100µg/ml with a correlation coefficient of 0.9985 Conclusion : No estimation techniques have been reported to date for the determination of this molecule. The proposed techniques may be used for the routine quantification in its pure form and also in presence of its parent drug molecule Ivabradine.

Field-induced domain wall motion has been observed in quasi-perpendicularly magnetized Pt/Co/Pt trilayers with interfacial Dzyaloshinskii-Moriya interaction (iDMI) using differential Kerr microscopy method in the creep regime. An oblique angle sputter deposition technique had introduced a thickness gradient in one of the layers of a trilyer, results in a small tilt of magnetic anisotropy from the film normal. The tilt angle has been estimated in each trilayer by determining the shift in the out-of-plane magnetization hysteresis measurements under bias magnetic field applied along various in-plane directions. The effective in-plane field at the domain wall due to iDMI has been determined by decomposing the symmetric and asymmetric contributions of the domain wall motion. Furthermore, the asymmetric contribution has been decomposed into two contributions due to the tilted magnetic anisotropy and the exponentially decaying chiral damping. The nature of the asymmetric contribution owing to the tilted anisotropy was studied by the collective coordinate model and a functional form of the total asymmetric contribution has been determined and used to fit the asymmetric contribution.

Epitaxial BiFeO(3)thin films with different thicknesses were grown on SrTiO3(001) substrate. The fllm exhibits a structural transformation from ``R-like'' phase with out-of-plane lattice parameter 4.06 ANGS; to a ``T-like'' phase with out-of-plane lattice parameter 4.65 ANGS; on increasing the thickness from 16 nm to 60 nm. The parasitic gamma Fe(2)O(3)phase was avoided by using slightly higher oxygen pressure during the growth. The ``R-like'' phase is shown to exhibit significant magnetic anisotropy and enhanced saturation magnetization which vanishes with the appearance of the ``T-like'' phase.

We report zero-field-cooled spontaneous-positive and field-cooled conventional-negative exchange bias effects in epitaxial bilayer composed of La0.7Sr0.3MnO3 (LSMO) with ferromagnetic (FM) and Eu0.45Sr0.55MnO3 (ESMO) with A-type antiferromagnetic (AF) heterostructures respectively. A temperature dependent magnetization study of LSMO/ESMO bilayers grown on SrTiO3 (001) manifest FM ordering (TC) of LSMO at ~320 K, charge/orbital ordering of ESMO at ~194 K and AF ordering (TN) of ESMO at ~150 K. The random field Ising model has demonstrated an interesting observation of inverse dependence of exchange bias effect on AF layer thickness due to the competition between FM-AF interface coupling and AF domain wall energy. The isothermally field induced unidirectional exchange anisotropy formed at the interface of FM-LSMO layer and the kinetically phase-arrested magnetic phase obtained from the metamagnetic AF-ESMO layer could be responsible for the spontaneous exchange bias effect. Importantly, no magnetic poling is needed, as necessary for the applications. The FM-AF interface exchange interaction has been ascribed to the AF coupling with $$\sum {J}_{ex}\vec{{S}_{{\rm{FM}}}}\cdot \vec{{S}_{{\rm{AF}}}}$$ ∑ J e x S FM ⃗ ⋅ S AF ⃗ ($${J}_{ex}\approx {J}_{AF}$$ J e x ≈ J A F , coupling constant between AF spins) for the spontaneous positive hysteresis loop shift, and the field-cooled conventional exchange bias has been attributed to the ferromagnetically exchanged interface with $${J}_{ex}\approx {J}_{F}$$ J e x ≈ J F (coupling constant between FM spins).

Exchange bias (EB) in a single magnetic film has always been an intriguing subject to the researchers. But the quest for the origin of EB in Fe3O4 films at temperatures, T

Various methods to induce beneficial residual stresses through controlled mechanical working on the surface of mechanical components are used to improve their fatigue life. Low Plasticity Burnishing (LPB) is one such technique gaining popularity compared to other similar technique due to the advantage of improving fatigue life without changing material and component design. Application of LPB to a specific component necessitates simulation of the process and evaluation of process parameters to get an insight into the depth, magnitude and distribution of induced beneficial residual stresses. Present work is an attempt to simulate ball indentation to evaluate process parameters and LPB simulation to predict induced beneficial stresses on the work piece surface. This simulation is used to evaluate the LPB induced residual stress distributions on the components made two different materials (Al 2024-T351 and Al 7075-7651) and three different indentation depths. Effect of different LPB process parameters on residual stress distributions are obtained from the FE simulations. The developed FE framework for simulation of indentation is further extended to adequately simulate LPB process to predict induced residual stresses.The evaluated residual stresses are useful for predicting fatigue life enhancement benefits derived from LPB.

Fatigue damage is one of the most prevalent failures around fastener holes of aircraft structures. The fatigue resistance of fastener holes is routinely enhanced through Split-Sleeve Cold Expansion. The extent of fatigue life improvement due to cold expansion depends on induced residual compressive stresses. In this work, a series of FE simulations were carried out for various levels of cold expansions around a hole in Al2024-T3 flat plate to analyze induced residual stresses. The improvement in fatigue performance due to induced residual stresses is predicted using Goodman’s theory and can be incorporated to achieve optimal designsof aircraft fastener joints.

Zr4+ doped multiferroic LuFeO3 (LFO) samples were prepared by a sol-gel reaction method and the effect of doping on structural, electric and magnetic properties are evaluated and compared with pure LFO. X-ray diffraction and Rietveld refinement confirm that the pure and Zr doped LFO exists in the hexagonal crystal structure with space group P63cm. The unit cell parameters and the volume of Zr0.2Lu0.8FeO3 (ZLFO) are greater than that of the undoped LFO. Magnetic measurements for ZLFO sample show a weak ferromagnetic-like behaviour at room temperature with M r ∼ 0.013 emu/g and finite coercivity. Hence, the paramagnetic LFO transformed to the weak ferromagnetic at room temperature upon Zr doping.

The structural, electric and magnetic properties of bulk hexagonal Lu1-x Sr x FeO3 (x = 0 and 0.15) ceramics are investigated. XRD data and rietveld refinement confirm the hexagonal structure with P63cm space group. Magnetic measurements for Sr-doped sample indicate a ferromagnetic-like behavior at the room temperature with a very high coercivity of the order of ∼ 4.4 kOe. P-E hysteresis loops show an enhanced ferroelectric property with Sr doping. Hence, towards the realization of applications, the multiferroic properties of hexagonal LuFeO3 are improved remarkably by 15% Sr substitution at Lu site.

We present a comprehensive study of the temperature (T) dependence of the longitudinal spin Seebeck effect (LSSE) in Pt/EuO1-x and Pt/La2NiMnO6 (LNMO) hybrid structures across their Curie temperatures (T-c). Both systems host ferromagnetic interaction below T-c, and hence present optimal conditions for testing magnon spin current based theories against ferrimagnetic yttrium iron garnet. Notably, we observe an anomalous Nernst effect generated voltage in bare EuO1-x, however, we find LSSE predominates the thermal signals in the bilayers with Pt. The T dependence of the LSSE in small T range near T-c could be fitted to a power law of the form (T-c- T)(p). The derived critical exponent P was verified for different methods of LSSE representation and sample crystallinity. The results are explained based on the magnon-driven thermal spin pumping mechanism that relates the T dependence of LSSE to the spin mixing conductance (G(mix)) at the heavy metal/ferromagnet interface, which in turn is known to vary inaccordance with the square of the spontaneous magnetization (M-s). Additionally, the T dependence of the real part of G(mix) derived from spin Hall magnetoresistance measurements at different temperatures for the Pt/LNMO structure further establishes the interdependence.

The magnetic proximity effect in top and bottom Pt layers induced by Co in Ta/Pt/Co/Pt multilayers has been studied by interface sensitive, element specific x-ray resonant magnetic reflectivity. The asymmetry ratio for circularly polarized x-rays of left and right helicity has been measured at the Pt $L_3$ absorption edge (11567 eV) with an in-plane magnetic field ($\pm158$ mT) to verify its magnetic origin. The proximity-induced magnetic moment in the bottom Pt layer decreases with the thickness of the Ta buffer layer. Grazing incidence x-ray diffraction has been carried out to show that the Ta buffer layer induces the growth of Pt(011) rather than Pt(111) which in turn reduces the induced moment. A detailed density functional theory study shows that an adjacent Co layer induces more magnetic moment in Pt(111) than in Pt(011). The manipulation of the magnetism in Pt by the insertion of a Ta buffer layer provides a new way of controlling the magnetic proximity effect which is of huge importance in spin-transport experiments across similar kind of interfaces., 7 pages, 9 figures

The effect of tool probe offset and varying traverse speed on the mechanical and metallographic characteristics of friction stir weld dissimilar joints of AA2024-T351 to AA7075-T651 in butt joint configuration produced using taper-threaded tool with constant tool rotation speed, 650 rpm and plunge depth, 6.2 mm are investigated. The tool traverse speed was varied from 20 to 120 mm/min along the weld length with the different tool probe offset condition. Optical microscopy and scanning electron microscopy are used to characterize the grain size and microstructural modification at the weld nugget zone (WNZ). The effect of different tool offset conditions in conjunction with varying traverse speed results in banded structure of alloys, partial material mixing and unmixed region at the WNZ. The combination of tool offset distance of 1 mm towards AA7075-T651 with traverse speed, 110 mm/min yields maximum ultimate tensile strength, 436 MPa, yield strength, 375 MPa, elongation, 14% and weld joint efficiency, 92%.

Artificial confinement of electrons by tailoring the layer thickness has turned out to be a powerful tool to harness control over competing phases in nano-layers of complex oxides. We investigate the effect of dimensionality on transport properties of $d$-electron based heavy-fermion metal CaCu$_{3}$Ru$_{4}$O$_{12}$. Transport behavior evolves from metallic to localized regime upon reducing thickness and a metal insulator transition is observed below 3 nm film thickness for which sheet resistance crosses $h/e^{2} \sim 25~$k$\Omega$, the quantum resistance in 2D. Magnetotransport study reveals a strong interplay between inelastic and spin-orbit scattering lengths upon reducing thickness, which results in weak antilocalization (WAL) to weak localization (WL) crossover in magnetoconductance., Comment: 10 pages, 4 figures

Interface effect in complex oxide thin-film heterostructures lies at the vanguard of current research to design technologically relevant functionality and explore emergent physical phenomena. While most of the previous works focus on the perovskite/perovskite heterostructures, the study of perovskite/brownmillerite interfaces remains in its infancy. Here, we investigate spontaneously stabilized perovskite-ferromagnet ($\mathrm{SrCo}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$)/brownmillerite-antiferromagnet $(\mathrm{SrCo}{\mathrm{O}}_{2.5})$ bilayer with ${T}_{\mathrm{N}}g{T}_{\mathrm{C}}$ and discover an unconventional interfacial magnetic exchange bias effect. From magnetometry investigations, it is rationalized that the observed effect stems from the interfacial ferromagnet/antiferromagnet coupling. The possibility for coupled ferromagnet/spin-glass interface engendering such effect is ruled out. Strikingly, a finite coercive field persists in the paramagnetic state of $\mathrm{SrCo}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$, whereas the exchange bias field vanishes at ${T}_{\mathrm{C}}$. We conjecture the observed effect to be due to the effective external quenched staggered field provided by the antiferromagnetic layer for the ferromagnetic spins at the interface. Our results not only unveil a paradigm to tailor the interfacial magnetic properties in oxide heterostructures without altering the cations at the interface, but also provide a purview to delve into the fundamental aspects of exchange bias in such unusual systems, paving a big step forward in thin-film magnetism.

Lead free (0.2) CoFe2O4 (CFO) – (0.8) Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) composite is prepared by mechanical mixing of CFO and BCZT phases. The constituent phases, CFO and BCZT are prepared by sol-gel technique. XRD data shows characteristic peaks of both magnetic and piezoelectric phases without any secondary phases confirming the formation of the composite. Polarization (P) versus Electric field (E) measurements show a proper ferroelectric loop for BCZT with P max ∼ 4.3 μC/cm2 whereas composite shows a leaky behaviour. Room temperature M-H loops show a decrease of magnetization from ∼ 80 emu/g for pure CFO to 17 emu/g for composite. Thus, 0.2 CFO-0.8 BCZT composite shows both electric and magnetic properties at room temperature.

In this work, we have studied the transport properties of two different single crystals, Sb2Te2Se and Sn-doped Sb2Te2Se. By analyzing the Shubnikov–de Haas oscillations for the devices made from both the crystals, we have extracted the Berry phase. The non-trivial value of the Berry phase for both the samples unambiguously indicates the robustness of the topological surface states against the impurity doping. The parent compound is n-type due to excess Te vacancies, and we could show from the sign of the intercept in the Landau level fan diagram and from the Hall effect measurements that doping with Sn makes it p-type. This demonstrates the tuning of the Fermi level in a topological insulator upon Sn doping.

It is well known that in double perovskites, the degree of cation ordering plays a very important role in determining the intrinsic magnetic properties. Therefore, in order to distinguish between the intrinsic properties and the disordered cation driven magnetic properties, we have grown ordered and disordered epitaxial thin films of Lu2MnNiO6 (LMNO) using two different cubic substrates (0 0 1)-LaAlO3 and (0 0 1)-SrTiO3 (LAO and STO respectively) by pulsed laser deposition (PLD) method. It is found that both LMNO films grow in monoclinic crystal symmetry and possess two out-of-plane domains (1 1 0) and (0 0 1). Moreover, various in-plane rotations of these domains give rise to a total of six in-plane twin variants. The films show dominant ferromagnetic nature. Due to good lattice matching with LAO, LMNO/LAO films are well-ordered and exhibit a sharp ferromagnetic to paramagnetic transition at TC = 38 K, whereas, the large lattice mismatch with STO resulted in disordered LMNO/STO films and TC is lowered to 34 K. The value of maximum magnetization (MS, at 70 kOe) in disordered LMNO/STO (MS = 2.4 μB/f.u.) is almost half of that in the ordered LMNO/LAO (MS = 4.0 μB/f.u.). Interestingly, the well-ordered LMNO/LAO films show memory effect and relaxation of magnetization in the entire temperature range below TC. This is in conformance to the intrinsic glassy magnetic nature of LMNO.

Epitaxial ferrimagnetic thin films of (Co, Ru) Fe2O4 were grown on MgO (001) substrate using pulsed laser deposition technique. Ruthenium substitution in cobalt ferrite has increased the conductivity by orders of magnitude, but it has a minimal effect on magnetic properties. The film has a high coercivity and perpendicular magnetic anisotropy (PMA), where the magnetic easy axis points perpendicular to the film surface. We report the magnetic and electrical transport properties here. The temperature variation of resistivity showed different conduction mechanisms at high and low-temperature regimes. Room temperature Hall measurement reveals “n” type carrier with a carrier concentration of 4×1020/cm3. The film showed negative MR and a linear decrement with the magnetic field without any saturation.

We studied the magnetoresistance of symmetric cobalt nanorings with nanowires attached at diametrically opposite positions. Deterministic switching, induced by an external magnetic field between the stable magnetization states, is demonstrated using histograms of the resistance changes as a function of an external magnetic field. The changes of the switching fields were studied as the lateral dimensions of these elements were varied systematically. The field required to switch between the vortex state and the onion state of the rings decreases as the line widths of the elements were increased. The vortex state is unstable at the larger line widths. Our experimental observations are explained using micromagnetic simulations.

Weak topological insulators are elusive topological materials that were subjected to relatively few experimental studies in the past owing to the lack of stable systems. Here, a detailed investigation of the low-temperature electrical transport on Bi 1 Se 1 thin films, a weak topological insulator, over a wide range of thicknesses has been carried out. Robust signatures of weak anti-localization were observed from the electrical transport measurements where the magnetic field is applied perpendicular and parallel to the sample plane. The low-field data are analyzed using the Hikami–Larkin–Nagaoka equation. By combining the transport parameters ( α, L ϕ) extracted from both perpendicular and parallel field measurements, our results indicate that apart from three-dimensional bulk states, 2D surface states are also present in our system and their origin could be linked to the weak topological nature of Bi 1 Se 1.

We report on the angular and field dependence of the magnetoresistance (MR) in bilayers of Pt / EuO 1 − x thin films, measured in both in-plane and out-of-plane geometries at different temperatures (T). The presence of oxygen vacancies manifested by a metal–insulator transition as well as a high-T ferromagnet-to-paramagnet transition (TP) was observed in the bilayers. The anisotropic magnetoresistance could be extracted in the entire T-range, even above TP, exhibiting two sign crossovers. We attribute its T-evolution to the rotation of the easy axis of the magnetization direction from a high-T out-of-plane to a low-T in-plane orientation. In addition, we provide direct experimental evidence of the spin Hall effect-induced spin Hall magnetoresistance, systematically considering several known MR contributions that can arise from the films' (111) texture and interface.