Liu<i>et al.</i>Reply:

Liu, Yu; Wang, Gang; Huang, Qingsong; Guo, Liwei; Chen, Xiaolong

doi:10.1103/physrevlett.110.029604

Cited by 106 publications

(168 citation statements)

References 1 publication

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“…The high structural flexibility of phase IV at pressures of 250-350 GPa and temperatures of 300-500 K has also been observed in previous ab initio variable-cell MD simulations, which found that the protons in the graphene-like layers can readily transfer to neighboring molecular sites via a simultaneous rotation of three-molecule rings. [56] Our results confirm that this behavior has a strong effect on the bandgaps of the C2=c and Pc structures. According to our band-gap energy results, the C2=c and Pc structures, thought to be the best candidates for phases III and IV of solid molecular hydrogen, [31] are metallic at room temperature and 300 GPa, in disagreement with most of the experimental evidence.…”

Section: Discussionsupporting

confidence: 84%

Nuclear quantum effects induce metallization of dense solid molecular hydrogen

2017

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We present an accurate computational study of the electronic structure and lattice dynamics of solid molecular hydrogen at high pressure. The band-gap energies of the C2/c, Pc, and P63/m structures at pressures of 250, 300, and 350 GPa are calculated using the diffusion quantum Monte Carlo (DMC) method. The atomic configurations are obtained from ab initio path-integral molecular dynamics (PIMD) simulations at 300 K and 300 GPa to investigate the impact of zero-point energy and temperature-induced motion of the protons including anharmonic effects. We find that finite temperature and nuclear quantum effects reduce the band-gaps substantially, leading to metallization of the C2/c and Pc phases via band overlap; the effect on the band-gap of the P63/m structure is less pronounced. Our combined DMC-PIMD simulations predict that there are no excitonic or quasiparticle energy gaps for the C2/c and Pc phases at 300 GPa and 300 K. Our results also indicate a strong correlation between the band-gap energy and vibron modes. This strong coupling induces a band-gap reduction of more than 2.46 eV in high-pressure solid molecular hydrogen. Comparing our DMC-PIMD with experimental results available, we conclude that none of the structures proposed is a good candidate for phases III and IV of solid hydrogen. © 2017 Wiley Periodicals, Inc.

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Section: Discussionsupporting

confidence: 84%

Nuclear quantum effects induce metallization of dense solid molecular hydrogen

2017

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“…In contrast to the propagating spin wave mode at I < I t , in this regime the oscillation exhibited a red shift with increasing current. Similar spectral features were previously observed in SHNO with in-plane magnetic anisotropy [20,21] and the conventional multilayer STNO [10], and were identified with the nonlinear selflocalized spin wave "bullet" mode [5]. With a further increase of current, an additional broad low-intensity peak emerges in the spectrum above I c = 12 mA, at frequency slightly below f F MR .…”

supporting

confidence: 81%

“…Traditionally, STT applications utilized magnetic multilayers, where the current exerting STT on the "free" magnetic layer was spin-polarized by a separate spinpolarizing ferromagnet [15,16]. More recently, an alternative, simpler and potentially more efficient approach has emerged [17][18][19][20][21], relying on spin currents produced by the spin Hall effect (SHE) [22], or on the spin-orbit torque (SOT) [23] exerted on the magnetic interface due to the Rashba effect [24]. These advancements have enabled the development of a novel type of STNO -the spin Hall nano-oscillator (SHNO) comprising a bilayer of an efficient spin Hall material and a ferromagnet (FM), without the need for a separate spin-polarizer [20,21].…”

mentioning

confidence: 99%

Dynamical Mode Coupling and Coherence in a Spin Hall Nano-Oscillator with Perpendicular Magnetic Anisotropy

Chen

Urazhdin

et al. 2019

Phys. Rev. Applied

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We experimentally study the dynamical modes excited by spin current in Spin Hall nano-oscillators based on the Pt/[Co/Ni] multilayers with perpendicular magnetic anisotropy. Both propagating spin wave and localized solitonic modes of the oscillation are achieved and controlled by varying the applied magnetic field and current. At room temperature, the generation linewidth broadening associated with mode hopping was observed at currents close to the transition between different modes and in the mode coexistence regimes. The mode hopping was suppressed at cryogenic temperatures, confirming that the coupling between modes is mediated by thermal magnons. We also demonstrate that coherent single-mode oscillations with linewidth of 5 MHz can be achieved without applying external magnetic field. Our results provide insight into the mechanisms controlling the dynamical coherence in nanomagnetic oscillators, and guidance for optimizing their applications in spin wave-based electronics.

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“…Furthermore, 2D tetragonal allotrope of C (T-graphene) originated from bct-carbon was predicted to be stable. Liu et al theoretically demonstrated that different from planar T-graphene, buckled T-graphene possess Dirac-like fermions and high Fermi velocity [12,13], while Huang et al claimed that buckled T-graphene is a normal metal as planar T-graphene [14]. Also, it was theoretically proposed that 2D tetragonal allotrope of Si (Tsilicene) is stable and is nodal line semimetal [15].…”

Section: Introductionmentioning

confidence: 99%

Topological node line semimetal state in two-dimensional tetragonal allotrope of Ge and Sn

Wang

Han

et al. 2019

New J. Phys.

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Realizing semimetal states in two-dimensional (2D) materials are of great importance for their future application in novel quantum devices at the nanoscale. Using first-principles calculations based on density functional theory, we propose a new 2D tetragonal allotrope of Ge and Sn, 2D T-Ge and T-Sn, which consists of repeated square and octagon rings. The calculated cohesive energy, ab initio molecular dynamic simulations and phonon dispersions indicate that 2D T-Ge and T-Sn are stable at room temperature and possibly synthesized in the experiments under appropriate growth conditions. In the absence of spin-orbital coupling (SOC), 2D T-Ge and T-Sn are node line semimetals and the nodal loop in 2D T-Ge and T-Sn are protected by the combination of the spatial inversion P and timereversal T symmetries. Remarkably, when SOC is included, 2D T-Ge and T-Sn are still node line semimetals although small gap is opened along the nodal loop, which are identified by nontrivial Z 2 invariant and topological edge states at the sample boundaries. Furthermore, our calculations show that node line semimetal states in 2D T-Ge and T-Sn are robust with the biaxial strains in the range of −3% to 3%. Our results provide a new 2D material platform for realization of 2D topological node line semimetals and innovative applications of topological node line semimetals.

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Liuet al.Reply:

Cited by 106 publications

References 1 publication

Nuclear quantum effects induce metallization of dense solid molecular hydrogen

Nuclear quantum effects induce metallization of dense solid molecular hydrogen

Dynamical Mode Coupling and Coherence in a Spin Hall Nano-Oscillator with Perpendicular Magnetic Anisotropy

Topological node line semimetal state in two-dimensional tetragonal allotrope of Ge and Sn

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