In this paper we report the phononic transport and its influence on thermal conductance in a one-dimensional random n-mer system. Based on an elastic wave equation, we studied frequency spectrum, phononic transmission, and thermal conductivity of the system. Multiple resonant transmissions are observed, which originate from delocalization of phonons in the correlated disorder system. At each resonant mode, zero-Lyapunov exponent and undecayed vibration of atoms have been found through the whole chain. Meanwhile channels are opened for phonon transmission and heat transport. As a result, thermal conductance is significantly enhanced at each resonant mode, forming a quantized feature as frequency increases. These properties demonstrate the possibility of manipulating phonon propagation and thermal conductance in phononic bandgap materials and may have potential applications in designing filter and waveguide for acoustic waves.
To search for half-metallic materials for spintronic applications, instead of using an expensive trial-and-error experimental scheme, it is more efficient to use first-principles calculations to design materials first, and then grow them. In particular, using a priori information of the structural stability and the effect of the spin–orbit interaction (SOI) enables experimentalists to focus on favorable properties that make growing half-metals easier. We suggest that using acoustic phonon spectra is the best way to address the stability of promising half-metallic materials. Additionally, by carrying out accurate first-principles calculations, we propose two criteria for neglecting the SOI so the half-metallicity persists. Based on the mechanical stability and the negligible SOI, we identified two half-metals, β-LiCrAs and β-LiMnSi, as promising half-Heusler alloys worth growing.
We theoretically studied the magnetostatic excitation in self-similar antiferromagnetic(AF)/nonmagnetic(NM) multilayers, where the AF and NM layers were arranged in a Thue-Morse sequence. The dispersion relation of magnetostatic spin waves and the precession amplitude of the total magnetization were achieved. It is shown that the distribution of eigenfrequencies possesses two bands of dual structures and each subband presents a hierarchical feature. The states in the finite system can be categorized to three types: critical states in the subband, extended states in the band, and localized surface states in the gaps. The multiformity in frequency spectra leads to the tunable magnetostatic wave, which may have potential applications in designing devices of magnetostatic waves for microwave communications.
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