Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei brings the optical transition energy into resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins - the nuclear spin nanomagnet.
A P-N junction engineered within a Dirac cone system acts as a gate tunable angular filter based on Klein tunneling. For a 3D topological insulator with substantial bandgap, such a filter can produce a charge-to-spin conversion due to the dual effects of spin-momentum locking and momentum filtering. We analyze how spins filtered at an in-plane topological insulator PN junction (TIPNJ) interact with a nanomagnet, and argue that the intrinsic charge-to-spin conversion does not translate to an external gain if the nanomagnet also acts as the source contact. Regardless of the nanomagnet's position…
Reply to Comment on "Acoustically assisted spin-transfer-torque switching of nanomagnets: An energy-efficient hybrid writing scheme for non-volatile memory" [Appl. Phys. Lett., 103, 232401 (2013)]
Energy dissipation and switching delay in spin-transfer torque switching of nanomagnets with low-saturation magnetization in the presence of thermal fluctuations
Using extensive numerical simulations, we probe the magnetization switching in two-dimensional artificial spin ice (ASI) system consisting of peanut-shaped nanomagnets. We also investigated the effect of the external magnetic field on the degeneracy of the magnetic states in such a system. The switching field is found to be one order smaller in the proposed ASI system with peanut-shaped nanomagnets as compared to the conventionally used highly-anisotropic nanoisland such as elliptically shaped nanomagnets. The metastable 2-in/2-out (Type II) magnetic state is robust at the remanence. We are al…
Magnetization reversal in a many-spin nanomagnet subjected to an rf magnetic field, on top of a DC magnetic field, is studied by numerically solving the system of coupled (damped) Landau-Lifshitz equations. It is demonstrated that spin-misalignment induced by surface anisotropy favors switching with a DC magnetic field weaker than the Stoner-Wohlfarth switching field, for optimal intensities and frequencies of the rf field.
It is demonstrated by means of the optimal control theory that the energy cost of the spin-orbit torque induced reversal of a nanomagnet with perpendicular anisotropy can be strongly reduced by proper shaping of both in-plane components of the current pulse. The time-dependence of the optimal switching pulse that minimizes the energy cost associated with Joule heating is derived analytically in terms of the required reversal time and material properties. The optimal reversal time providing a tradeoff between the switching speed and energy efficiency is obtained. A sweet-spot balance between th…
Features and Peculiarities of Gate-Voltage Modulation of Spin-Orbit Interaction in FeCoB Nanomagnets: Insights into the Physical Origins of the VCMA Effect
Hybrid magneto-dynamical modes in a single magnetostrictive nanomagnet on a piezoelectric substrate arising from magneto-elastic modulation of precessional dynamics
The spins, which are accumulated at a boundary of a nanomagnet due to the Spin Hall effect, induce a magnetic field, which tilts the nanomagnet magnetization out of its easy axis. Even though this magnetic field is relatively small (about 20 Gauss), it can reverse the magnetization of the nanomagnet if it is modulated in resonance with the magnetization precession and the conditions of the parametric resonance are met. Therefore, such magnetic field can be used to optimize the recording mechanism and to minimize the recording energy for MRAM. A high-precession measurement method of the spin-ac…
Altermagnetic Magnons in Dipolar Nanomagnet Arrays
Universität Münster（明斯特大学）；Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau（莱茵兰-普法尔茨凯泽斯劳滕-兰道技术大学）；Radboud University（拉德堡德大学）；Johannes Gutenberg University Mainz（约翰内斯·古腾堡美因茨大学）
Angular Dependent Magnetization Dynamics with Mirror-symmetric Excitations in Artificial Quasicrystalline Nanomagnet Lattices
我们报道了非周期准晶磁晶格的角度相关自旋波光谱，即，Ammann、Penrose P2和P3晶格由互连的Ni $_{80}$ Fe $_{20}$纳米棒的大阵列制成。自旋波光谱中获得的近饱和状态包含不同的组的共振特性的角度依赖性所施加的面内磁场。微磁模拟使我们能够将检测到的共振归因于具有特定镜像对称性的模式分布。在反转制度的光谱显示系统的出现和消失的自旋波模式，表明可重编程的磁振子特性。
Quantum impurity (QI) spins offer promising information processing and sensing applications by harnessing up to room-temperature quantum coherence. Challenged by the requirement of designing local coherent drives and improving sensitivity to various signals for such applications, the search of hybrid systems coupling QI spins with matter excitations have garnered significant recent interest. We propose and theoretically study a hybrid system that couples spin-1 QI with the dynamical excitations of nanomagnets, which are controlled by mechanisms uncovered in classical spintronics. We show that …
