Nonlinear NMR and magnon BEC in antiferromagnetic materials with coupled electron and nuclear spin precession
Nonlinear NMR and magnon BEC in antiferromagnetic materials with coupled electron and nuclear spin precession
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DOI：
10.1103/physrevb.97.024425
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发表时间：
2018-01-22
影响因子：
3.7
通讯作者：
Tankeyev, A. P.
中科院分区：
文献类型：
--
作者：
Abdurakhimov, L. V.;Borich, M. A.;Tankeyev, A. P.
本文研究了反铁磁MnCO_3中电子与核自旋耦合的非线性核磁共振和核自旋波的玻色-爱因斯坦凝聚（BEC）。特别是，我们发现，所观察到的行为的NMR信号强烈矛盾的传统描述的顺磁系综的非相互作用的自旋的基础上的唯象布洛赫方程。我们提出了一个耦合的电子核自旋进动的理论描述，其中考虑到通过电子子系统的核自旋的间接弛豫。我们发现，任意大的激发功率，这是从传统的加热方案从布洛赫方程的显着不同的核磁化的幅度是保守的。这为实验观测到的宏观核磁共振的相干旋进可以与k = 0的核自旋波的BEC相一致提供了有力的证据。
We present a study of nonlinear NMR and Bose-Einstein condensation (BEC) of nuclear spin waves in antiferromagnetic MnCO3 with coupled electron and nuclear spins. In particular, we show that the observed behavior of NMR signals strongly contradicts the conventional description of paramagnetic ensembles of noninteracting spins based on the phenomenological Bloch equations. We present a theoretical description of the coupled electron-nuclear spin precession, which takes into account an indirect relaxation of nuclear spins via the electron subsystem. We show that the magnitude of the nuclear magnetization is conserved for arbitrary large excitation powers, which is drastically different from the conventional heating scenario derived from the Bloch equations. This provides strong evidence that the coherent precession of macroscopic nuclear magnetization observed experimentally can be identified with the BEC of nuclear spin waves with k = 0.