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arXiv 1302.4460cond-mat.str-el
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量子磁体中圆极化laser诱导的磁化和相变

Magnetization and phase transition induced by circularly polarized laser in quantum magnets

Shintaro Takayoshi, Hideo Aoki, Takashi Oka

摘要:

我们从理论上预言了激光诱导量子自旋系统的非平衡相变,这提供了一个纯粹的量子力学相干控制磁化的方式。也就是说,当一个圆偏振激光施加到自旋系统,激光的磁分量示出,以诱导垂直于偏振平面的磁化,导致超快相变。我们首先证明了这种现象的数值$S=1$反铁磁海森堡自旋链,其中出现了一个新的状态与磁化垂直的偏振平面的激光在拓扑有序的Halfenstein状态。然后,我们阐明其物理机制,通过映射系统到一个有效的静态模型。理论还表明,这种现象应该发生在一般的具有磁各向异性的量子自旋系统中。所需的激光频率在太赫兹范围内,所需的强度在预期的实验可行性范围内。

英文摘要:

We theoretically predict a nonequilibrium phase transition in quantum spin systems induced by a laser, which provides a purely quantum-mechanical way of coherently controlling magnetization. Namely, when a circularly polarized laser is applied to a spin system, the magnetic component of a laser is shown to induce a magnetization normal to the plane of polarization, leading to an ultrafast phase transition. We first demonstrate this phenomenon numerically for an $S=1$ antiferromagnetic Heisenberg spin chain, where a new state emerges with magnetization perpendicular to the polarization plane of the laser in place of the topologically ordered Haldane state. We then elucidate its physical mechanism by mapping the system to an effective static model. The theory also indicates that the phenomenon should occur in general quantum spin systems with a magnetic anisotropy. The required laser frequency is in the terahertz range, with the required intensity being within a prospective experimental feasibility.

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