Yuan Wei, Zhu Qiong, Su Tang, Yao Yunyan, Xing Wenyu, Chen Yangyang, Ma Yang, Lin Xi, Shi Jing, Shindou Ryuichi, Xie X C, Han Wei
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China.
Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China.
Sci Adv. 2018 Apr 13;4(4):eaat1098. doi: 10.1126/sciadv.aat1098. eCollection 2018 Apr.
Spin superfluid is a novel emerging quantum matter arising from the Bose-Einstein condensate (BEC) of spin-1 bosons. We demonstrate the spin superfluid ground state in canted antiferromagnetic CrO thin film at low temperatures via nonlocal spin transport. A large enhancement of the nonlocal spin signal is observed below 20 K, and it saturates from ~5 down to 2 K. We show that the spins can propagate over very long distances (20 μm) in such spin superfluid ground state and that the nonlocal spin signal decreases very slowly as the spacing increases with an inverse relationship, which is consistent with theoretical prediction. Furthermore, spin superfluidity has been investigated in the canted antiferromagnetic phase of the (11[Formula: see text]0)-oriented CrO film, where the magnetic field dependence of the associated critical temperature follows a / power law near the critical point. The experimental demonstration of the spin superfluid ground state in canted antiferromagnet will be extremely important for the fundamental physics on the BEC of spin-1 bosons and paves the way for future spin supercurrent devices, such as spin-Josephson junctions.
自旋超流体是一种由自旋为1的玻色子的玻色-爱因斯坦凝聚（BEC）产生的新型量子物质。我们通过非局域自旋输运在低温下的倾斜反铁磁CrO薄膜中演示了自旋超流基态。在约20 K以下观察到非局域自旋信号大幅增强，并且从约5 K到2 K饱和。我们表明，自旋在这种自旋超流基态中可以在很长距离（约20μm）上传播，并且随着间距以反比关系增加，非局域自旋信号下降非常缓慢，这与理论预测一致。此外，已经在（11[公式：见正文]0）取向的CrO薄膜的倾斜反铁磁相中研究了自旋超流性，其中相关临界温度的磁场依赖性在临界点附近遵循/幂律。倾斜反铁磁体中自旋超流基态的实验演示对于自旋为1的玻色子的玻色-爱因斯坦凝聚的基础物理学极为重要，并为未来的自旋超流器件，如自旋-约瑟夫森结，铺平了道路。
