Institute for Condensed Matter Physics and Complex Systems, DISAT, Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy.
Phys Rev Lett. 2012 Dec 7;109(23):236404. doi: 10.1103/PhysRevLett.109.236404. Epub 2012 Dec 5.
We characterize the Mott-insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These nonlocal quantities order in the corresponding gapped phases and vanish at the critical point U(c)=0, thus configuring as hidden order parameters. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at U(c). The behavior of the parity correlators is captured by an effective free spinless fermion model.
我们通过关联函数来描述一维 Hubbard 模型的莫特绝缘相和 Luther-Emery 相，这些关联函数测量链上自旋和电荷字符串的奇偶性。这些非局域量在相应的能隙相中有序，在临界点 U(c)=0 处消失，因此构成了隐藏的序参量。莫特绝缘相由束缚的双电子-空穴对组成，而在 Luther-Emery 相中，这些束缚对转变成具有相反自旋的电子对，在 U(c)处它们都被解除束缚。奇偶关联函数的行为可以通过有效的无自旋费米子模型来捕捉。
