Modulating effect of pair-hopping and spin exchange interactions on a half-filled generalized U–V chain

2014 ◽  
Vol 28 (06) ◽  
pp. 1450042 ◽  
Author(s):  
Hanqin Ding ◽  
Jun Zhang
Keyword(s):  
Charge Density ◽  
Spin Density ◽  
Charge Density Wave ◽  
Nearest Neighbor ◽  
Spin Exchange ◽  
Density Wave ◽  
Spin Density Wave ◽  
Exchange Interactions ◽  
Bond Charge ◽  
Pair Hopping

In this paper, we study analytically a half-filled generalized Hubbard chain with a quite general nearest-neighbor interaction, parametrized by diagonal repulsion V, off-diagonal pair-hopping and correlated-hopping repulsions W, X and antiferromagnetic spin exchange J for small values of the interactions. The ground state phase diagram is obtained in the weak-coupling regime. Besides the charge-density-wave (CDW) and spin-density-wave (SDW) phases for large 2V/U and U/2V, respectively, we identify a bond-spin-density-wave (BSDW) for J/W < 2, 3J/2 - 2W < 2V - U < 2W - J/2 and bond-charge-density-wave (BCDW) phase for J/W > 2, 2W - J/2 < 2V - U < 3J/2 - 2W. The modulating effect of W and J is responsible for the emergence of BSDW and BCDW phases, which, however, are decreased weakly by the Umklapp scattering of parallel-spin electrons.

Phase diagram of an extended t-U-J chain with frustrated exchange interaction

2014 ◽  
Vol 28 (32) ◽  
pp. 1450228
Author(s):  
Hanqin Ding ◽  
Jun Zhang
Keyword(s):  
Phase Diagram ◽  
Charge Density ◽  
Charge Density Wave ◽  
Nearest Neighbor ◽  
Spin Exchange ◽  
Density Wave ◽  
Spin Density Wave ◽  
Effective Field ◽  
J Chain ◽  
Bond Charge

Using the low-energy effective field theory scenario combined Abelian bosonization and renormalization-group techniques, we study the Hubbard chain with additional anisotropic nearest-neighbor and isotropic next-nearest-neighbor spin exchanges J and J′ in the weak-coupling regime. The spin correlations are non-critical due to the anisotropic J (Jxy ≠ Jz). The frustrating antiferromagnetic exchange J′ leads to an enhancement of the dimerized phase and induces a long-range charge-density-wave (CDW) phase. For smaller values of J′ (J′ < 2U/3), the quantum phase diagram consists of the insulating spin-density-wave ( SDW xy, SDW z) and bond-charge-density-wave (BCDW) phases and the triplet superconducting ( TS 0, TS ±) phase. For larger J′ (J′ ≥ 2U/3), a finite CDW phase appears. The result shows that the frustrated spin exchange J′ changes the topological structure of the usual t-U-J chain.

scholarly journals Superconductivity in the doped Hubbard model and its interplay with next-nearest hopping t′

Science ◽  
2019 ◽  
Vol 365 (6460) ◽  
pp. 1424-1428 ◽  
Author(s):  
Hong-Chen Jiang ◽  
Thomas P. Devereaux
Keyword(s):  
Hubbard Model ◽  
Charge Density ◽  
Spin Density ◽  
Charge Density Wave ◽  
Large Scale ◽  
Nearest Neighbor ◽  
High Temperature Superconductivity ◽  
Density Wave ◽  
Spin Density Wave ◽  
Hole Doping

The Hubbard model is widely believed to contain the essential ingredients of high-temperature superconductivity. However, proving definitively that the model supports superconductivity is challenging. Here, we report a large-scale density matrix renormalization group study of the lightly doped Hubbard model on four-leg cylinders at hole doping concentration δ = 12.5%. We reveal a delicate interplay between superconductivity and charge density wave and spin density wave orders tunable via next-nearest neighbor hopping t′. For finite t′, the ground state is consistent with a Luther-Emery liquid with power-law superconducting and charge density wave correlations associated with half-filled charge stripes. In contrast, for t′ = 0, superconducting correlations fall off exponentially, whereas charge density and spin density modulations are dominant. Our results indicate that a route to robust long-range superconductivity involves destabilizing insulating charge stripes in the doped Hubbard model.

PHASE DIAGRAM OF THE ONE-DIMENSIONAL t–U–J MODEL WITH ON-BOND REPULSION AT HALF FILLING

2010 ◽  
Vol 24 (32) ◽  
pp. 6307-6322 ◽  
Author(s):  
HANQIN DING ◽  
YANSHEN WANG
Keyword(s):  
Phase Diagram ◽  
Charge Density ◽  
Spin Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Spin Density Wave ◽  
Metallic Phase ◽  
Flow Diagram ◽  
One Dimensional ◽  
Bond Charge

By using the bosonization approach and the renormalization group (RG) technique, we study the half-filled band one-dimensional t–U–J model with additional on-bond repulsion (W>0) in the weak-coupling regime. The presence of on-bond repulsion is responsible for realization of a metallic phase in the system, and the phase diagram is strongly controlled by the symmetry of the model. By analyzing the RG flow diagram and comparing order parameters, the phase boundaries are determined and the structure of the phase diagram is clarified. In the case of SU (2) ⊗ SU (2) symmetry, the phase diagram consists of a metallic phase characterized by a Luttinger liquid (LL) and two insulting phases characterized by the degenerate spin-density-wave (SDW) and the bond-charge-density-wave (BCDW). In the SU (2) ⊗ U(1)-symmetric case, the phase diagram contains two metallic phases: a LL and a Luther–Emery phase, and three insulating phases: the transverse SDW ( SDW ±), the longitudinal SDW ( SDW z) and the dimerized BCDW. The insulating charge-density-wave and bond-spin-density-wave (BSDW) phases are always suppressed in the ground state. In addition, the system show a long-ranged order in the BCDW and SDW z phases.

Charge Density Wave Accompanied by Spin Density Wave in Mn3Si

2014 ◽  
Vol 83 (4) ◽  
pp. 044715 ◽  
Author(s):  
Shoichi Tomiyoshi ◽  
Hiroyuki Ohsumi ◽  
Hisao Kobayashi ◽  
Akiji Yamamoto
Keyword(s):  
Charge Density ◽  
Spin Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Spin Density Wave

IMPURITY EFFECTS ON THE MAGNETIC ORDERING IN CHROMIUM

1993 ◽  
Vol 07 (01n03) ◽  
pp. 620-623 ◽  
Author(s):  
R.S. FISHMAN ◽  
S.H. LIU
Keyword(s):  
Charge Density ◽  
Spin Density ◽  
Charge Density Wave ◽  
Second Harmonic ◽  
Density Wave ◽  
Spin Density Wave ◽  
Order Transition ◽  
Vanadium Concentration ◽  
First Order ◽  
First Order Transition

It is well-known that impurities profoundly alter the magnetic properties of chromium. While vanadium impurities suppress the Néel temperature TN, manganese impurities enhance TN substantially. As evidenced by neutron scattering experiments, doping with as little as 0.2% vanadium changes the transition from weakly first order to second order. Young and Sokoloff explained that the first-order transition in pure chromium is caused by a charge-density wave which is the second harmonic of the spin-density wave. By examining the subtle balance between the spin-density and charge-density wave terms in the mean-field free energy, we find that the first-order transition is destroyed when the vanadium concentration exceeds about 0.15%, in agreement with experiments.

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