Dimov Ivailo, Halperin Bertrand I, Nayak Chetan
Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547, USA.
Phys Rev Lett. 2008 Mar 28;100(12):126804. doi: 10.1103/PhysRevLett.100.126804. Epub 2008 Mar 27.
We consider quantum Hall states at even-denominator filling fractions, especially nu=5/2, in the limit of small Zeeman energy. Assuming that a paired quantum Hall state forms, we study spin ordering and its interplay with pairing. We give numerical evidence that at nu=5/2 an incompressible ground state will exhibit spontaneous ferromagnetism. The Ginzburg-Landau (GL) theory for the spin degrees of freedom of paired Hall states is a perturbed CP2 model. We compute the coefficients in the GL theory by a BCS Stoner mean-field theory for coexisting order parameters, and show that even if repulsion is smaller than that required for a Stoner instability, ferromagnetic fluctuations can induce a partially or fully polarized superconducting state.
我们考虑在小塞曼能量极限下，具有偶数分母填充因子的量子霍尔态，特别是ν = 5/2 。假设形成了配对量子霍尔态，我们研究自旋序及其与配对的相互作用。我们给出了数值证据，表明在ν = 5/2时，不可压缩基态将表现出自发铁磁性。用于配对霍尔态自旋自由度的金兹堡 - 朗道（GL）理论是一个微扰的CP2模型。我们通过用于共存序参量的BCS - 斯托纳平均场理论计算GL理论中的系数，并表明即使排斥力小于斯托纳不稳定性所需的值，铁磁涨落也可诱导部分或完全极化的超导态。
