论文标题
Bloch Fermagnetism
Bloch Ferromagnetism of Composite Fermions
论文作者
论文摘要
1929年，菲利克斯·布洛克（Felix Bloch）提出，磁磁性的电子海洋应在非常低的密度下自发过渡到完全磁性状态，因为对齐旋转获得的交换能量超过了动能的增强。我们在这里报告了一个突然的，相互作用驱动的向完全磁化的过渡，这使人联想起Bloch铁磁剂，这在过去的90年中一直在避免了实验。我们的平台是最低兰道水平半填充的奇异二维费米海。通过对旋转极化的直接度量的费米波向量的定量测量，我们观察到从部分旋转的偏振到完全旋转的基层状态的突然过渡，因为我们降低了复合材料的密度。我们的详细理论计算提供了对此现象的半定量描述。
In 1929 Felix Bloch suggested that the paramagnetic Fermi sea of electrons should make a spontaneous transition to a fully-magnetized state at very low densities, because the exchange energy gained by aligning the spins exceeds the enhancement in the kinetic energy. We report here the observation of an abrupt, interaction-driven transition to full magnetization, highly reminiscent of Bloch ferromagnetism that has eluded experiments for the last ninety years. Our platform is the exotic two-dimensional Fermi sea of composite fermions at half-filling of the lowest Landau level. Via quantitative measurements of the Fermi wavevector, which provides a direct measure of the spin polarization, we observe a sudden transition from a partially-spin-polarized to a fully-spin-polarized ground state as we lower the composite fermions' density. Our detailed theoretical calculations provide a semi-quantitative account of this phenomenon.
