Hidden competing phase revealed by first-principles calculations of phonon instability in the nearly optimally doped cuprate La1.875Sr0.125CuO4
| Autor: | Chi-Cheng Lee, Ji-Yao Chiu, Yukiko Yamada-Takamura, Taisuke Ozaki |
|---|---|
| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Physical Review B. 104 |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.104.064114 |
| Popis: | The representative cuprate ${\mathrm{La}}_{2\ensuremath{-}x}{M}_{x}{\mathrm{CuO}}_{4}$ with $M=\mathrm{Sr}$ and $x=1/8$ is studied via first-principles calculations in the high-temperature tetragonal (HTT), low-temperature orthorhombic (LTO), and low-temperature less-orthorhombic (LTLO) structures. By suppressing the magnetism and superconductivity, the LTLO phase, which has rarely been observed in ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$, is found to be the ground state where the structural phase transitions $\mathrm{HTT}\ensuremath{\rightarrow}\mathrm{LTO}\ensuremath{\rightarrow}\mathrm{LTLO}$ can be understood via phonon instability. Although the La-O composition is identified to be responsible for the phonon softening, the superconducting ${\mathrm{CuO}}_{2}$ layer is dynamically stable. The LTLO phase, which can exhibit an $\ensuremath{\sim}20\text{\ensuremath{-}}\mathrm{meV}$ splitting in the density of states, is proposed to have an intimate relationship with the observed pseudogap and the charge-density wave giving the stripe. We argue that at low temperatures, the superconducting LTO ${\mathrm{La}}_{1.875}{\mathrm{Sr}}_{0.125}{\mathrm{CuO}}_{4}$ competes with the phonon-preferred LTLO phase by spontaneously forming the Cooper pairs, resulting in suppressing the stripe. Therefore, the revealed LTLO phase is indispensable for understanding ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|