论文标题
具有PT对称性的两旋链系统的非热动力学
Non-Hermitian dynamics of a two-spin system with PT symmetry
论文作者
论文摘要
可以使用复杂的功能性或非热（NH）哈密顿量来描述一种在自旋极化电流影响下的相互作用自旋的系统。我们研究了Bloch球上两个交换耦合旋转的动力学。在导致PT对称性的电流的情况下，在非线性系统中也存在一个特殊点。非线性系统可用于小电流，并且表现出稳定的振荡运动，或者可以放松到固定点。两次旋转的振荡运动类似于同步自旋旋转振荡器。对于完整的非线性系统，我们得出了两个保守的数量，这些量提供了相位空间中自旋轨迹的几何描述，并表明振荡运动的稳定性。我们的分析结果为描述Bloch球体定义的NH系统动力学提供了工具。
A system of interacting spins that are under the influence of spin-polarized currents can be described using a complex functional, or a non-Hermitian (NH) Hamiltonian. We study the dynamics of two exchange-coupled spins on the Bloch sphere. In the case of currents leading to PT symmetry, an exceptional point that survives also in the nonlinear system is identified. The nonlinear system is bistable for small currents and it exhibits stable oscillating motion or it can relax to a fixed point. The oscillating motion of the two spins is akin to synchronized spin-torque oscillators. For the full nonlinear system, we derive two conserved quantities that furnish a geometric description of the spin trajectories in phase space and indicate stability of the oscillating motion. Our analytical results provide tools for the description of the dynamics of NH systems that are defined on the Bloch sphere.
