تقرير
High density of states in the pseudogap phase of the cuprate superconductor HgBa$_2$CuO$_{4 + \delta}$
| العنوان: | High density of states in the pseudogap phase of the cuprate superconductor HgBa$_2$CuO$_{4 + \delta}$ |
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| المؤلفون: | Girod, Clément, Legros, Anaëlle, Forget, Anne, Colson, Dorothée, Marcenat, Christophe, DeMuer, Albin, LeBoeuf, David, Taillefer, Louis, Klein, Thierry |
| المصدر: | Phys. Rev. B 102 (2020) 014506 |
| سنة النشر: | 2020 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons |
| الوصف: | The specific heat $C$ of the single-layer cuprate superconductor HgBa$_2$CuO$_{4 + \delta}$ 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 $\gamma = 12 \pm 2$ 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 $\gamma$ 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$_{6 + \delta}$ at $p \simeq 0.3$, where $\gamma \simeq 7$ mJ/K$^2$mol. Given that the pseudogap causes a loss of density of states, and assuming that HgBa$_2$CuO$_{4 + \delta}$ has the same $\gamma$ value as other cuprates at $p \simeq 0.3$, this implies that $\gamma$ in HgBa$_2$CuO$_{4 + \delta}$ 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 $\gamma$ value implies that the Fermi surface must consist of more than the single electron-like pocket detected by quantum oscillations in HgBa$_2$CuO$_{4 + \delta}$ at $p \simeq 0.09$, whose effective mass $m^\star= 2.7\times m_0$ yields only $\gamma = 4.0$ 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. Comment: 8 pages, 5 figures |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1103/PhysRevB.102.014506 |
| URL الوصول: | http://arxiv.org/abs/2004.03650 |
| رقم الأكسشن: | edsarx.2004.03650 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1103/PhysRevB.102.014506 |
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