Competition between Charge- and Spin-Density-Wave Order and Superconductivity inLa1.875Ba0.125−x

Abstract

We have performed a series of elastic neutron scattering measurements on 1/8-hole doped La1.875Ba0.125−xSrxCuO4 single crystals with x = 0.05, 0.06, 0.075 and 0.085. Both charge-densitywave (CDW) and spin-density-wave (SDW) orders are found to develop simultaneously below the structural transition temperature between the low-temperature orthorhombic (LTO) and lowtemperature tetragonal (LTT) or low-temperature less-orthorhombic (LTLO) phases. In the ground state the CDW order is observed only in the LTT/LTLO phase and drastically degrades towards the LTO boundary. The x-dependence of Tc strongly suggests a direct effect of the CDW order on the suppression of superconductivity. Results are discussed in comparison with those from the La1.6−xNd0.4SrxCuO4 system within the framework of the stripe model. PACS numbers: 74.72. Dn, 71.45.Lr, 75.30.Fv, 74.25.Dw The interplay between magnetism and superconductivity is a central issue in high-T c superconductivity [1]. Neutron scattering measurements on the superconducting La 2−x Sr x CuO 4 (LSCO) system have shown dynamical incommensurate (IC) magnetic correlation [2][3][4]. The linear doping dependence of incommensurability with the superconducting transition temperature (T c ) in the under-doped region suggests a relationship between magnetic correlation and superconductivity [5].On the other hand, it is well known that superconductivity in the La 2−x M x CuO 4 (M=Ba, Sr) system is anomalously suppressed at the specific hole concentration of x ∼1/8. For the La 2−x Ba x CuO 4 (LBCO) system, this 1/8-anomaly is accompanied by an occurrence of the lowtemperature tetragonal (LTT) phase with P4 2 /ncm symmetry [6][7][8]. Superconductivity in the low-temperature orthorhombic (LTO) phase of LSCO with Bmab symmetry is weakly suppressed in comparison with the LBCO system [9,10]. Maeno et al. initiated systematic studies on La 1.875 Ba 0.125−x Sr x CuO 4 (LBSCO) using polycrystalline samples to clarify the relation between T c and crystal structure [11]. We comprehensively studied the same system using single crystals and revealed a drastic change in x-dependence of T c [12,13]. In the present study we demonstrate a close relation between T c and crystal structure as shown in Fig.4.Recently, the IC spin-density-wave (SDW) and the charge-density-wave (CDW) orders were discovered in La 1.6−x Nd 0.4 Sr x CuO 4 (LNSCO) with x ∼ 1/8. These provide important clues for understanding the mechanism of the 1/8-anomaly based on the stripe model [14,15]. In the framework of the stripe model it is recognized that the orders are a manifestation of dynamical spin/charge correlation and that stabilization of the orders competitively induces instability of superconductivity [16]. In the LTT phase stripe-shaped orders parallel or perpendicular to Cu-O bonding are favorably stabilized by the corrugated pattern of the in-plane lattice potential. Hence, T c is suppressed to a greater extent in the LTT phase than in the LTO phase. Whether visible signs, such as the anomalous suppression of T c , app...

High-resolution x-ray scattering studies of structural phase transitions in underdopedLa2−xBaxCuO4Zhao1, Gaulin2, Castellan3 et al. 2007Phys. Rev. B261270View full textAdd to dashboardCite

“…This shows that the LTT phase is either an admixture of a tetragonal and an orthorhombic phase, as was suggested by electron microscopy on an earlier generation of La 2−x Ba x CuO 4 crystals 27 , or that it is itself othorhombic with a very small orthorhombic strain. In either case it is not as "tetragonal" as the HTT phase, and is consistent with the "less orthorhombic" low temperature structures proposed previously for La 2−x Sr x−y Ba y CuO 4 single crystals 28 .…”

Spatially modulated 'Mottness' in La2-xBaxCuO4

“…4). Charge correlations were visible at both edges below the LTT transition at 60 K, which is higher than previously published 6 because the x value for our sample is closer to 1/8 (ref. 26).…”

Magnetic Field Effect on the Static Antiferromagnetism of the Electron-Doped SuperconductorPr1−xLaCFujita1, Matsuda2, Katano3 et al. 2004Phys. Rev. Lett.Self Cite313262View full textAdd to dashboardCite

“…A recent nuclear magnetic resonance study [28] for optimally doped PLCCO also predicted the Fermi-liquid ground state. Therefore, the magnetism in the n-type cuprate near the AF-SC phase boundary can be regarded as the weak itinerant antiferromagnet, in contrast to that in the hole doped cuprates in which magnetic interaction is robust against doping due to the charge segregation into stripes [29,30]. The shift of T m by magnetic field suggests the field dependence of the quantum critical concentration for the magnetic order.…”