Freezing of spin and charge inLa2−xSrxCu

Abstract

Zeroand longitudinal-field muon-spin relaxation (it+ SR) measurements have been performed on La2-Sr"Cu04 alloys in both single-crystal and sintered powder forms above and below their magnetic transition temperatures, Tf. The p+ precession frequency v depends only weakly on x and Tf, an observation which together with resistivity data implies classical freezing of magnetic moments in the regime where the carriers are localized. For x 0.05, critical dynamics are observed near Tf. The p SR technique is shown to be very sensitive to ferromagnetically aligned pairs of Cu + moments; the population of such pairs increases greatly with x. Over the past year or so, various cuprates have been found to be superconducting with transition temperatures (T, 's) as high as -90 K. ' Bulk investigations of related compounds, such as La2Cu04 s, have also been performed in the hope that they may provide a basis for understanding the superconducting materials. Neutron scattering experiments have confirmed the existence of antiferromagnetism and its sensitivity to oxygen stoichiometry in LazCu04 s. In the present paper, we describe a detailed study of magnetic order in the La2, Sr,Cu04 series, precursors to the superconducting systems that are obtained for x ) 0.06. We have chosen to use the muon-spin relaxation (p+ SR) technique because

Slow spin-glass and fast spin-liquid components in quasi-two-dimensionalLa2(Cu,Li)O4

“…A similar magnetic phase diagram has also been reported for La 2−x Sr x CuO 4 and Y 1−x Ca x Ba 2 Cu 3 O 6 [11,12,13]. In conventional spin glasses, magnetic interactions are more or less isotropic in space, and the whole spin system is believed to be frozen in the spin-glass phase [14].…”

An Intrinsic Bond-Centered Electronic Glass with Unidirectional Domains in Underdoped Cuprates

“…The superconductivity usually does not appear until n ~ 5 to 10%. Therefore, another low-temperature state intervenes; it is usually thought of as an electronic "cluster glass" (ECG) state (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). At higher dopings, the ECG signatures coexist with diminishing intensity with the strengthening superconductivity, until they disappear somewhere near n ~ 15%.…”

“…At higher dopings, the ECG signatures coexist with diminishing intensity with the strengthening superconductivity, until they disappear somewhere near n ~ 15%. Although the ECG state exhibits no known long range spin or charge order, some electronic order of unknown spatial form is always detected at nm scale by local probes of the spin (8)(9)(10)(11)(12)(13)(14)(15) and charge (14-20) -hence the "cluster" designation. And, because it is from this ECG state that high temperature superconductivity emerges with hole doping (22), it is critical to determine what it is, how it is generated by hole doping, and how it evolves into and coexists with the superconducting state.…”

Muon Spin Rotation in High TcSuperconductors

“…For such materials the magnetism was found in the series of zero field µSR experiments [28,33,34]. The example of temperature dependence of µSR frequencies in these materials is shown in Fig.…”

“…Harshman et al [33] extended their μSR studies of La2-x Srx CuO4 onto longitudinal-field decoupling experiments. Especially, for x = 0.05 and temperature just above ordering temperature they found that the μSR signal "is a sum of two components: one (derived from magnetic fluctuations) freezes and yields muon-spin precession at low temperatures, and another (due to a set of apparently stronger moments) that do not yield a precession signal".…”