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  • Carroll Mejer posted an update 3 weeks ago

    In this paper a systematic study is carried out to demonstrate the structural stability and magnetic novelty of adsorbing transition metal (TM) dimers (A-B) on graphyne (GY) surface, GY@A-B. Our research points out that the dimers are strongly adsorbed onto GY due to their large natural pores and the electron affinity of the sp-hybridized carbon atoms. Electronic properties of these dimer-graphyne composite systems are of particular importance as they behave as degenerate semiconductors with partial occupation of states atEF. Furthermore, their remarkable spin polarization (>80%) at Fermi energy (EF) can be of paramount importance in spintronics applications. Most of the GY@A-B structures exhibit large magnetic anisotropies as well as magnetic moments along the out-of-plane direction with respect to the GY surface. Particularly, GY@Co-Ir, GY@Ir-Ir and GY@Ir-Os structures possess positive magnetic anisotropic energies (MAE) of 121 meV, 81 meV and 137 meV, respectively, which are comparable to other well-known TM dimer doped systems. The emergence of high MAE can be understood using the second-order perturbation theory on the basis of the strong spin-orbit coupling (SOC) between the two TMs and the degeneracy of their d-orbitals nearEF. A close correspondence between the simulated and the analytical results has been established through our work. Further, a simple estimation shows that, GY@A-B structures have the potential to store data up to 64 PB m-2. These intriguing electronic characteristics along with magnetism suggest GY@A-B to be a promising material for future magnetic storage devices.Near-field radiative heat transfer (NFRHT) governed by evanescent waves, provides a platform to thoroughly understand the transport behavior of nonradiative photons, and also has great potential in high-efficiency energy harvesting and thermal management at the nanoscale. There have been numerous and impactful progresses of theories and experiments in terms of NFRHT in two-body systems. However, it is more usual in nature that objects participate in heat transfer process in many-body form rather than the frequently-considered two-body scenarios, and the inborn mutual interactions among objects are important to be understood and utilized for practical applications. Therefore, the issue of many-body NFRHT on aspects of theories and applications becomes increasingly explored. selleck screening library The last decade has witnessed considerable achievements on many-body NFRHT, ranging from the establishment of different calculation methods to various unprecedented heat transport phenomena that are distinct from two-body systems. In this invited Review, we introduce concisely the basic physics of NFRHT, lay out various theoretical methods to deal with many-body NFRHT, and highlight unique functionalities realized in many-body systems and the resulting applications. At last, the key challenges and opportunities of many-body NFRHT in terms of fundamental physics, experimental validations, and potential applications are outlined and discussed.An adiabatic transition between two equilibrium states corresponding to different stiffnesses in an infinite chain of particles is studied. Initially, the particles have random displacements and random velocities corresponding to uniform initial temperature distributions. An instantaneous change in the parameters of the chain initiates a transitional process. Analytical expressions for the chain temperature as a function of time are obtained from statistical analysis of the dynamic equations. It is shown that the transition process is oscillatory and that the temperature converges non-monotonically to a new equilibrium state, in accordance with what is usually unexpected for thermal processes. The analytical results are supplemented by numerical simulations.We report a comprehensive study on the magnetic, electrical and thermal properties of Ni100-xTM x (TM= V, Cr, Nb,) alloys around their critical concentration. Analysis of field and temperature dependence magnetization data suggests a weak itinerant ferromagnetic behavior inx= 8 and 10 compositions and the ferromagnetic ordering suppresses in the concentration range 10 less then x less then 12. Further, the temperature dependence of specific heat shows an unusual low temperature variation with an enhanced Sommerfeld coefficient,γ, with a signature of non-Fermi-liquid (NFL) behavior close to critical concentration. Further, the enhancement in Kadowaki-Woods ratio suggests it to be a strongly correlated electron system near critical concentration. Present analysis of experimental data consistently revealed that the NFL behavior is caused by spin fluctuations near critical concentration. The temperature dependencies of the electrical resistivity, the magnetization and linear term of the electronic specific heat appear to follow the theoretical predictions of a quantum phase transition and it is tempting to suggest that the presently studies Ni-rich alloys can be candidates for the observation of Griffith phase.Embedding magnetic particles within polymer matrix is a common and facile method to fabricate magnetically responsive micro-/nanoscale pillars. However, the balance between mechanical compliance and magnetic susceptibility cannot be decoupled and the particles are limited by the pillar feature size, which can limit the actuation performance. Here we demonstrate a new type of magnetically responsive nanostructure consisting of a polydimethylsiloxane (PDMS) nanopillar array with deposited nickel caps, that has successfully achieved such decoupling with multiple cap-geometry designs for a better actuation control. The actuation result of nanopillars with 540 nm period and 1.3 μm height has been analyzed using image processing, leading to a maximum displacement of 180 nm with a ratio of 13.9% with respect to the pillar height. Magnetic and mechanical models based on magnetic force and torque have been developed and used to mitigate the weakening effect of the actuation by the residual magnetic layer. This structure demonstrates a feasible strategy for magnetic actuation at the sub-micrometer scale with freedom to design magnetic cap and polymeric pillar separately. This structure can also be utilized in multiple applications such as tunable optical elements, dynamic droplet manipulation, and responsive particle manipulation.

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