Microscopic evidence for the intra-unit-cell electronic nematicity inside the pseudogap phase in YBa_2Cu_4O_8
Microscopic evidence for the intra-unit-cell electronic nematicity inside the pseudogap phase in YBa_2Cu_4O_8
复制标题
YBa2Cu4O8 赝能隙相内晶胞内电子向列性的微观证据
DOI：
10.1007/s11433-020-1615-y
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Zheng Guoqing
中科院分区：
文献类型：
--
作者：
Wang Wen;Luo Jun;Wang Chunguang;Yang Jie;Kodama Yasuharu;Zhou Rui;Zheng Guoqing
理解神秘的赝能隙现象的本质是与铜氧化物高温超导体相关的最重要的问题之一。用~（17）O核磁共振（NMR）研究了化学计量比的铜氧化物YBa_2Cu_4O_3中的两个平面氧位。我们观察到在高温下两个氧位的Knight位移是相同的但在T_（nem）~ 185 K（接近赝能隙温度T_（max））以下，两个氧位的四极共振频率差没有变化，说明向列性不是由局域电荷密度调制直接引起的，这为单胞内电子向列性提供了微观证据。在T = 150 K以下观察到一个短程电荷密度波（CDW）序，由此引起的~（17）O-NMR谱的额外增宽对于两个氧位是不等价的，这与向列性的情况相似，这些结果表明向列性、CDW序伪Gap
Understanding the nature of the mysterious pseudogap phenomenon is one of the most important issues associated with cuprate high-T_c superconductors.Here,we report ~(17)O nuclear magnetic resonance (NMR) studies on two planar oxygen sites in stoichio- metric cuprate YBa_2Cu_4O_8 to investigate the symmetry breaking inside the pseudogap phase.We observe that the Knight shifts of the two oxygen sites are identical at high temperatures but different below T_(nem) ~ 185 K,which is close to the pseudogap temperature T∗.Our result provides a microscopic evidence for intra-unit-cell electronic nematicity.The difference in quadrupole resonance frequency between the two oxygen sites is unchanged below T_(nem),which suggests that the observed nematicity does not directly stem from the local charge density modulation.Furthermore,a short-range charge density wave (CDW) order is observed below T ≃ 150 K.The additional broadening in the ~(17)O-NMR spectra because of this CDW order is determined to be inequivalent for the two oxygen sites,which is similar to that observed in case of nematicity.These results suggest a possible connection between nematicity,CDW order,and pseudogap.