Magnetic Droplet Soliton Nucleation in Oblique Fields

Designing Magnetic Droplet Soliton Nucleation Employing Spin Polarizer

We show by means of micromagnetic simulations that spin polarizer in nano-contact spin torque oscillators (NC-STOs) as the representative of the fixed layer in an orthogonal pseudo-spin valve (P-SV) can be employed to design and to control magnetic droplet soliton nucleation and dynamics. We found that using a tilted spin polarizer layer decreases the droplet nucleation time which is more suitable for high speed applications. However, a tilted spin polarizer increases the nucleation current and decreases the frequency stability of the droplet. Additionally, by driving the magnetization inhomog…

Steady-State Homogeneous Nucleation and Growth of Water Droplets: Extended Numerical Treatment

The steady-state homogeneous vapor-to-liquid nucleation and the succeeding liquid droplet growth process are studied for water system by means of the coarse-grained molecular dynamics simulations with the mW-model suggested originally in [Molinero, V.; Moore, E. B. \textit{J. Phys. Chem. B} \textbf{2009}, \textit{113}, 4008-4016]. The investigation covers the temperature range $273 \leq T/K \leq 363$ and the system's pressure $p\simeq 1$ atm. The thermodynamic integration scheme and the extended mean first passage time method as a tool to find the nucleation and cluster growth characteristics …

Direct observation of magnetic droplet solitons in all-perpendicular spin torque nano-oscillators

Magnetic droplets are non-topological dynamical solitons that can be nucleated and sustained in nano-contact based spin torque nano-oscillators (NC-STNOs) with perpendicular anisotropy free layers. While originally predicted in all-perpendicular NC-STNOs, all experimental demonstrations have so far relied on orthogonal devices with an in-plane polarizing layer that requires a strong magnetic field for droplet nucleation. Here, we instead show the nucleation and sustained operation of magnetic droplets in all-perpendicular NC-STNOs in modest perpendicular fields and over a wide range of nano-co…

A fingerprint of surface-tension anisotropy in the free-energy cost of nucleation

We focus on the Gibbs free energy $ΔG$ for nucleating a droplet of the stable phase (e.g. solid) inside the metastable parent phase (e.g. liquid), close to the first-order transition temperature. This quantity is central to the theory of homogeneous nucleation, since it superintends the nucleation rate. We recently introduced a field theory describing the dependence of $ΔG$ on the droplet volume $V$, taking into account besides the microscopic fuzziness of the droplet-parent interface, also small fluctuations around the spherical shape whose effect, assuming isotropy, was found to be a charact…

可视化金属介导的氮化镓及合金的成核与生长

Visualizing metal-mediated nucleation and growth of GaN

研究通过E-TEM和吉布斯自由能计算揭示金属介导的GaN成核与生长机制，强调Ga/GaN界面在促进NH3分解和GaN生长中的关键作用。

Molecular Dynamics Study of Droplets on Flat Crystalline Surface during Cooling and Ice formation

Condensation and frost formation degrade the heat transfer performance of air-conditioners and refrigerators. Yet, the frost formation mechanism has not been fully understood. In the present study, we numerically investigated H2O droplets during cooling and ice formation by means of classical molecular dynamics simulations. The mW potential was employed for the H2O molecules. A nanoscale H2O droplet was placed on a flat solid wall consisting of Pt atoms. The fcc (110) crystal plane faced the droplet. We examined where ice nucleation was formed and how the ice formation proceeded inside the dro…