Phonon and Thermal Properties of Quasi-Two-Dimensional FePS3 and MnPS3 Antiferromagnetic Semiconductor Materials
Fariborz Kargar, Ece Aytan, Subhajit Ghosh, Jonathan Lee, Michael Gomez, Yuhang Liu, Andres Sanchez Magana, Zahra Barani Beiranvand, Bishwajit Debnath, Richard … 展开作者
Fariborz Kargar, Ece Aytan, Subhajit Ghosh, Jonathan Lee, Michael Gomez, Yuhang Liu, Andres Sanchez Magana, Zahra Barani Beiranvand, Bishwajit Debnath, Richard Wilson, Roger K. Lake, Alexander A. Balandin
We report results of investigation of the phonon and thermal properties of the exfoliated films of layered single crystals of antiferromagnetic FePS3 and MnPS3 semiconductors. The Raman spectroscopy was conducted using three different excitation lasers with the wavelengths of 325 nm (UV), 488 nm (blue), and 633 nm (red). The resonant UV-Raman spectroscopy reveals new spectral features, which are not detectable via visible Raman light scattering. The thermal conductivity of FePS3 and MnPS3 thin films was measured by two different techniques: the steady-state Raman optothermal and transient time-resolved magneto-optical Kerr effect. The Raman optothermal measurements provided the orientation-average thermal conductivity of FePS3 to be 1.35 W/mK at room temperature. The transient measurements revealed that the through-plane and in-plane thermal conductivity of FePS3 is 0.85 W/mK and 2.7 W/mK, respectively. The films of MnPS3 have higher thermal conductivity of 1.1 W/mK through-plane and 6.3 W/mK in-plane. The data obtained by both techniques reveal strong thermal anisotropy of the films and the dominant contribution of phonons to heat conduction. Our results are important for the proposed applications of the antiferromagnetic semiconductor thin films in spintronic devices.
Electron-phonon scatterings in solid-state systems are pivotal processes in determining many key physical quantities such as charge carrier mobilities and thermal conductivities. Here, we report on the direct probing of phonon mode specific electron-phonon scatterings in layered semiconducting transition metal dichalcogenides WSe2, MoSe2, WS2, and MoS2 through inelastic electron tunneling spectroscopy measurements, quantum transport simulations, and density functional calculation. We experimentally and theoretically characterize momentum-conserving single- and two-phonon electron-phonon scatte…
Two-dimensional intrinsic antiferromagnetic semiconductors are expected to stand out in the spintronic field. The present work finds the monolayer T'-MoTeI is intrinsically an antiferromagnetic semiconductor by using first-principles calculation. Firstly, the dimerized distortion of the Mo atoms causes T'-MoTeI to have dynamic stability, which is different from the small imaginary frequency in the phonon spectrum of T-MoTeI. Secondly, T'-MoTeI is an indirect-bandgap semiconductor with 1.35 eV. Finally, in the systematic study of strain effects, there are significant changes in the electronic s…
We study theoretically the contribution of quantum effects to the exciton diffusion coefficient in atomically thin crystals. It is related to the weak localization caused by the interference of excitonic wavefunctions on the trajectories with closed loops. Due to a weak inelasticity of the exciton-phonon interaction the effect is present even if the excitons are scattered by long-wavelength acoustic phonons. We consider exciton interaction with longitudinal acoustic phonons with linear dispersion and with flexural phonons with quadratic dispersion. We identify the regimes where the weak locali…
Phonon wind and drag of excitons in monolayer semiconductors
从理论上研究了过渡金属双硫族化合物单层膜中激子的非平衡输运。我们考虑激子与非平衡声子相互作用的情况，例如，在局部激发的条件下形成“热点”。我们发展了声子对激子拖曳的理论，并详细分析了声子的扩散传播和声子的弹道传播的声子风形成的制度。我们证明了类似于在[Phys. Rev. Lett. 120，207401（2018）]可以由于非平衡声子或塞贝克效应的激子拖曳而形成。
Interplay between in-plane and flexural phonons in electronic transport of two-dimensional semiconductors
平面外振动被认为是在低载流子浓度下限制悬浮二维材料的本征载流子迁移率的主要因素。面内声子模和弯曲声子模之间的非谐耦合通常被排除在考虑之外。本文提出了一种电子-声子散射理论，其中系统地考虑了声学声子之间的非谐耦合。我们的理论适用于典型的V族二维半导体：六角磷，砷，锑。我们发现，弯曲模式的作用基本上是抑制他们的耦合与平面模式。当掺杂量小于10 $^{12}$ cm $^{-2}$时，迁移率的降低不超过30%，几乎与浓度无关。我们的研究结果表明，在平面声子相比，弯曲声子是相当不重要的二维半导体的电子输运，即使在低载流子浓度。
The ab-initio theory of charge transport in semiconductors typically employs the lowest-order perturbation theory in which electrons interact with one phonon (1ph). This theory is accepted to be adequate to explain the low-field mobility of non-polar semiconductors but has not been tested extensively beyond the low-field regime. Here, we report first-principles calculations of the electric field-dependence of the electron mobility of Si as described by the warm electron coefficient, $β$. Although the 1ph theory overestimates the low-field mobility by only around 20%, it overestimates $β$ by ov…
In organic semiconductors working under ambient circumstance, there are remarkable quantum effects lack of comprehensive understanding, and an exotic composite particle named charge transfer (CT) exciton is normally regarded as the key ingredient. Another essential substance is the phonons stemming from intra- and inter-molecular vibrations, and the relevant diagonal electron-phonon couplings give rise to spatial localization and the off-diagonal couplings refer to the dispersion of electron wavefunctions. In this work, we first propose a toy model based upon the fracton physics to phenomenolo…
Weak antiferromagnetic (AF) interaction in the ferromagnetic (FM) partially ordered La2CoMnO6 (LCMO) was detected by Raman spectroscopy by monitoring spin-phonon coupling. Because of the sensibility to probe short-range disorder and lattice modifications, the Raman spectroscopy showed to be an useful tool to indicate less remarkable magnetic transitions in LCMO compound. Apart from the expected spin-phonon coupling due to the long-range FM superexchange (Tc~230 K), phonons parameters pointed out an additional spin-phonon coupling related to the short-range AF interaction at Tc~135 K, which was…
