Effect of the soft layer thickness on magnetization reversal process of exchange-spring nanomagnet patterns

A systematic study of the magnetization reversal behavior in the regular arrangement of L1₀-FePt based exchange-spring nanomagnets with different thicknesses of the Co soft magnetic layer is presented. The magnetic property of the hard magnet is compared to two tuned exchange-spring magnets: its systems of 20 nm L1₀-FePt/3 nm, and 7 nm Co. In particular, we focus on the switching field distribution. The exchange coupling showed narrower SFD, in spite of the decoupled part switches earlier. The magnetization switching mechanism of exchange-spring nanomagnets patterns has been revealed with a first-order reversal curves technique and the switching field distribution. Further, the microscopic results using magnetic force microscopy show that the spin rotation of the non-interacting part in the thicker soft layered exchange-spring magnet. The part influences the magnetization reversal process. According to the experimental results, exchange coupling strength can be tuned by the thickness of the soft magnetic layer.     

Distinct ferroelectric domain switching dynamics in epitaxial BiFeO3 (001) capacitors depending on the bias polarity

Understanding ferroelectric domain switching dynamics at the nanoscale is a great of importance in the viewpoints of fundamental physics and technological applications. Here, we investigated the intriguing polarity-dependent switching dynamics of ferroelectric domains in epitaxial BiFeO₃ (001) capacitors using transient switching current measurement and piezoresponse force microscopy. We observed the distinct behavior of nucleation and domain wall motion depending on the polarity of external electric bias. When applying the negative bias to the top electrode, the sideways domain wall motion initiated by only few nuclei was dominant to polarization switching. However, when applying the positive bias, most of domains started to grow from the pre-existed pinned domains and their growth velocity was much smaller. We suggest that the observed two distinct domain switching behavior is ascribed to the interfacial defect layer.     

CONTINUOUS DEPENDENCE OF THE SOLUTIONS OF IMPULSIVE DIFFERENTIAL EQUATIONS ON THE INITIAL CONDITIONS AND BARRIER CURVES＊

The basic objects of investigation in this article are nonlinear impulsive differential equations.The impulsive moments coincide with the moments of meeting of the integral curve and some of the so-cal...     

GeCl分子激发态的势能曲线和辐射寿命的理论研究

采用考虑Davidson校正、标量相对论效应、芯-价电子关联和自旋-轨道耦合效应高精度的多参考组态相互作用方法计算了GeCl分子的最低解离极限Ge(3Pg)+Cl(2Pu)对应的12个Λ-S电子态的势能曲线. 基于计算得到的势能曲线, 求解一维核运动的Sch?rdinger方程得出束缚态的光谱常数, 这些光谱常数与实验值符合较好. 本文计算了12个Λ-S态的电偶极矩随核间距的变化, 分析了电子态组态成分的变化对电偶极矩的影响. 本文还研究了GeCl分子的辐射跃迁性质, 给出了激发态到基态之间和低激发态之间的跃迁偶极矩和电子态之间的Franck-Condon因子, 并根据计算得到的跃迁偶极矩和Franck-Condon因子计算出了束缚激发态低振动能级的辐射寿命.