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arXiv 1310.0109cond-mat.str-el
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低维共振价键液体

Resonating-valence-bond liquid in low dimensions

Fusayoshi J. Ohkawa

摘要:

基于Kondo晶格理论,研究了具有在位排斥$U$和最近邻迁移积分$-t/\sqrt{D}$的$D$维Hubbard模型.如果$U/|t| \gg 1$,$|n - 1| \lesssim |t|/(DU)$,其中$n$是每个晶胞的电子数,并且$D$如此小,使得$|J|/D \gg k_{\rm B}T_c$,其中$J = -4t^2/U$和$T_c$是$D = 1$的$0 {\rm K}$,并且是$D \ge 2$的可能的临界温度中的最高临界温度,低- $T$相,其中$T_c < T \ll |J|/(k_{\rm B}D)$是受抑电子液体。由于这种液体是通过近藤效应和共振价键(RVB)机制稳定的,所以它只是RVB电子液体;在一维中,它也是Tomonaga-Luttinger液体。RVB液体的近藤能量为$k_{\rm B}T_{\rm K} = O(|J|/D)$ ;其有效费米能量为$O(k_{\rm B}T_{\rm K})$。在上、下哈伯德带之间的化学势上出现一个中带,哈伯德能隙是一个赝能隙。关于中带的每单位晶胞的态密度,其带宽是$O(k_{\rm B}T_{\rm K})$或$O(|J|/D)$,其峰高是$O(1/U)$,并且其谱权重是$O[t^2/(DU^2)]$。由于在海森伯极限中,中间带几乎消失,因此在海森伯极限中的RVB电子液体仅仅是RVB自旋液体。RVB电子和自旋液体彼此连续。由于局部矩形成于高$T$相,其中$T \gtrsim T_{\rm K}$,高$T$相就是莫特绝缘体.

英文摘要:

The Hubbard model in $D$ dimensions, with the on-site repulsion $U$ and the transfer integral between nearest neighbors $-t/\sqrt{D}$, is studied on the basis of the Kondo-lattice theory. If $U/|t| \gg 1$, $|n - 1| \lesssim |t|/(DU)$, where $n$ is the number of electrons per unit cell, and $D$ is so small that $|J|/D \gg k_{\rm B}T_c$, where $J = -4t^2/U$ and $T_c$ is $0 {\rm K}$ for $D = 1$ and is the highest critical temperature among possible ones for $D \ge 2$, a low-$T$ phase where $T_c < T \ll |J|/(k_{\rm B}D)$ is a frustrated electron liquid. Since the liquid is stabilized by the Kondo effect in conjunction with the resonating-valence-bond (RVB) mechanism, it is simply the RVB electron liquid; in one dimension, it is also the Tomonaga-Luttinger liquid. The Kondo energy of the RVB liquid is $k_{\rm B}T_{\rm K} = O(|J|/D)$; its effective Fermi energy is $O(k_{\rm B}T_{\rm K})$. A midband appears on the chemical potential between the upper and lower Hubbard bands; the Hubbard gap is a pseudogap. As regards the density of states per unit cell of the midband, its bandwidth is $O(k_{\rm B}T_{\rm K})$ or $O(|J|/D)$, its peak height is $O(1/U)$, and its spectral weight is $O[t^2/(DU^2)]$. Since the midband almost disappears in the Heisenberg limit, the RVB electron liquid in the Heisenberg limit is simply the RVB spin liquid. The RVB electron and spin liquids adiabatically continue to each other. Since local moments form in a high-$T$ phase where $T \gtrsim T_{\rm K}$, the high-$T$ phase is simply the Mott insulator.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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