Charge-carrier density and interplane coupling in Y2Ba4Cu7O15: A Cu NMR-NQR study.
Charge-carrier density and interplane coupling in Y2Ba4Cu7O15: A Cu NMR-NQR study.
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Y2Ba4Cu7O15 中的载流子密度和面间耦合：Cu NMR-NQR 研究。
DOI：
10.1103/physrevb.50.426
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Muller
中科院分区：
文献类型：
--
作者：
Raivo Stern;Mali;Mangelschots;Roos;Brinkmann;Genoud;Graf;Muller
本文报道了Y2Ba4Cu7O15中Cu63，65核四极共振和核磁共振的观测结果.我们已经测量的温度依赖性的铜NQR频率和自旋晶格弛豫在所有四个化学不等价的铜网站，和铜磁移在两个不等价的平面铜网站（磁场平行和垂直于c轴）。结果表明，Y2Ba4Cu7O15化合物是由两个不同掺杂水平的CuO2晶面组成的结构，是由YBa2Cu4O8和YBa2Cu3O7两个晶面交替组成的多点阵结构。在正常的导电状态下的静态和动态电子自旋极化率的双平面的各个平面是由相同的温度依赖性，这表明了一个典型的低掺杂的高Tc化合物的行为。相同的温度依赖性意味着这些平面之间的强耦合，耦合常数的下限不小于30 meV。虽然这些平面是强耦合的，但它们的自旋极化率保持着明显的q依赖性。弛豫速率和奈特位移的温度变化描述的自旋间隙的形成，或者，受挫相分离。低于Tc，共同的温度依赖性丢失，这可能是由于两个超导间隙的开放，在各个平面上不同。
We report an observation of the Cu 6 3, 6 5 nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR) in Y 2 Ba 4 Cu 7 O 15. We have measured the temperature dependence of the Cu NQR frequency and spin-lattice relaxation at all four chemically inequivalent Cu sites, and of the Cu magnetic shift at two inequivalent plane Cu sites (for the magnetic field parallel and perpendicular to the c axis). The Y 2 Ba 4 Cu 7 O 15 compound turns out to be a structure containing two inequivalent CuO 2 planes of differing doping levels, a multilattice in which YBa 2 Cu 4 O 8 blocks and YBa 2 Cu 3 O 7 blocks alternate. In the normal conducting state both the static and the dynamic electron spin susceptibilities of the individual planes of a double plane are governed by the same temperature dependence, which shows a behavior typical for an underdoped high-T c compound. The same temperature dependence means strong coupling between these planes, with the lower limit of the coupling constant not much less than 30 meV. Although the planes are strongly coupled, their spin susceptibilities retain a distinct q dependence. The temperature variation of relaxation rate and Knight shift is described in terms of spin-gap formation or, alternatively, of frustrated phase separation. Below T c, the common temperature dependence is lost, which could arise from the opening of two superconducting gaps that differ in the individual planes.