论文标题
冷费米气体的自旋极化铁磁状态
The spin-polarized ferromagnetic state of a cold Fermi gas
论文作者
论文摘要
研究了冷费米气体的自旋偏振铁磁状态，用于相互作用和非相互作用的电荷中性和$β$平衡的气体。磁场和费米子的电荷和磁偶极矩之间的标准最小耦合定义了费米子与磁场的相互作用。假设磁场和费米昂（Baryon）偶极矩之间具有可变的耦合强度，则表明可以实现铁磁性状态，该状态与磁场完全归因于气体的磁力响应，对应于较低的能量自旋偏振状态。我们发现，取决于密度，需要大幅度增加BARYON偶极矩才能达到这种铁磁性状态。虽然所需的增加似乎不太可能，但感应磁场是$ \ sim10^{17} $高斯的顺序。此外，虽然外部磁化的费米气体具有各向异性压力，但铁磁性气体的压力是完全各向同性的，并且热力学优选的磁化态。
The spin-polarized ferromagnetic state of a cold Fermi gas is investigated for interacting and non-interacting charge-neutral and $β$-equilibrated gases. The standard minimal couplings between the magnetic field and the fermions' charges and magnetic dipole moments define the fermions' interaction with the magnetic field. Assuming a variable coupling strength between the magnetic field and the fermion (baryon) dipole moments, it is shown that a ferromagnetized state can be achieved that corresponds to a lower energy spin-polarized state with a magnetic field entirely due to the gas's magnetic response. We find that, depending on the density, a very large increase in the baryon dipole moments is needed to achieve this ferromagnetized state. While the required increase seems unlikely, the induced magnetic field is of the order $\sim10^{17}$ gauss. Furthermore, while externally magnetized Fermi gases have an anisotropic pressure, the pressure of the ferromagnetized gas is completely isotropic and the thermodynamically preferred magnetized state.
