论文标题
在库层超导体HGBA的伪库中，状态的高密度$ _2 $ cuo $ _ {4 +δ} $
High density of states in the pseudogap phase of the cuprate superconductor HgBa$_2$CuO$_{4 + δ}$
论文作者
论文摘要
单层杯形的特定热量$ c $ hgba $ _2 $ cuo $ _ {4 +δ} $在被压倒式的水晶中测量，$ t _ {\ rm c} = 72 $ k = 72 $ k在磁场上的磁性降低到$ 35 $ t的$ 35 $ t，以$ 2 $ t，以$ 35 $ t的范围， \ simeq 0.09 $）。在$ h = 35 $ t时的正常状态下，剩余的线性量级$γ= 12 \ pm 2 $ mj/k $^2 $ mol以$ c/t $为$ c/t $ as $ t \ to 0 $，这是对国家电子密度的直接度量。 $γ$的高价值具有两个主要影响。首先，它明显大于伪库阶段以外的过量的库酸盐（$ p> p> p^\ star $），例如la $ _ {2-x} $ _x $ _x $ _x $ _x $ cuo $ _4 $ _4 $和tl $ _2 $ _2 $ ba $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _3 $γ\ simeq 7 $ mj/k $^2 $ mol。假设伪gap会导致状态密度损失，并且假设hgba $ _2 $ cuo $ _ {4 +δ} $具有与其他cuprates相同的$γ$值，则$ p \ simeq 0.3 $，这意味着$γ$ in hgba $ _2 $ cuo $ pecu $ pecu $ pecue $ p p p p p pe p p p p pe p p p p pe p $ p p p p p \ p p \ pe p \ p p \ s + n +Δ $ p \ simeq 0.3 $，即（或接近）关键掺杂$ p^\ star $，其中伪随机阶段有望结束（$ p^\ star \ simeq 0.2 $）。其次，高$γ$值意味着费米表面必须由hgba $ _2 $ _2 $ _2 $ cuo $ _ {4 +δ} $ at $ p \ simeq 0.09 $检测到的单个电子口袋组成。这种缺失的质量对当前情况进行了修改，以分别为伪造和电荷顺序分别转化和重建丘比特的费米表面。
The specific heat $C$ of the single-layer cuprate superconductor HgBa$_2$CuO$_{4 + δ}$ was measured in an underdoped crystal with $T_{\rm c} = 72$ K at temperatures down to $2$ K in magnetic fields up to $35$ T, a field large enough to suppress superconductivity at that doping ($p \simeq 0.09$). In the normal state at $H = 35$ T, a residual linear term of magnitude $γ= 12 \pm 2$ mJ/K$^2$mol is observed in $C/T$ as $T \to 0$, a direct measure of the electronic density of states. This high value of $γ$ has two major implications. First, it is significantly larger than the value measured in overdoped cuprates outside the pseudogap phase ($p >p^\star$), such as La$_{2-x}$Sr$_x$CuO$_4$ and Tl$_2$Ba$_2$CuO$_{6 + δ}$ at $p \simeq 0.3$, where $γ\simeq 7$ mJ/K$^2$mol. Given that the pseudogap causes a loss of density of states, and assuming that HgBa$_2$CuO$_{4 + δ}$ has the same $γ$ value as other cuprates at $p \simeq 0.3$, this implies that $γ$ in HgBa$_2$CuO$_{4 + δ}$ must peak between $p \simeq 0.09$ and $p \simeq 0.3$, namely at (or near) the critical doping $p^\star$ where the pseudogap phase is expected to end ($p^\star\simeq 0.2$). Secondly, the high $γ$ value implies that the Fermi surface must consist of more than the single electron-like pocket detected by quantum oscillations in HgBa$_2$CuO$_{4 + δ}$ at $p \simeq 0.09$, whose effective mass $m^\star= 2.7\times m_0$ yields only $γ= 4.0$ mJ/K$^2$mol. This missing mass imposes a revision of the current scenario for how pseudogap and charge order respectively transform and reconstruct the Fermi surface of cuprates.
