Direct observation of a one-dimensional static spin modulation in insulating La{sub 1.95}Sr{sub 0.05}CuO{sub 4}
- Department of Physics and Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
- National Institute of Standards and Technology, NCNR, Gaithersburg, Maryland 20889 (United States)
- Institute for Chemical Research, Kyoto University, Gokasho, Uji 610-0011, (Japan)
- Department of Physics, Tohoku University, Sendai 980-8578, (Japan)
We report the results of an extensive elastic neutron-scattering study of the incommensurate (IC) static spin correlations in La{sub 1.95}Sr{sub 0.05}CuO{sub 4}, which is an insulating spin glass at low temperatures. Recent work by Wakimoto et al. has revealed the presence of new two-dimensional satellite peaks in La{sub 1.95}Sr{sub 0.05}CuO{sub 4} at positions rotated by {approx}45 degree sign in reciprocal space from those found in superconducting samples. The present neutron-scattering experiments on the same x=0.05 crystal employ a narrower instrumental Q resolution and thereby have revealed that the crystal has only two, rather than four, orthorhombic twins at low temperatures with relative populations of 2:1. This has made possible the precise characterization of the IC elastic peaks around (1,0,0) and (0,1,0) (orthorhombic notation) in each domain separately. We find that, in a single twin, only two satellites are observed at (1,{+-}0.064,L){sub ortho} and (0,1{+-}0.064,L){sub ortho}, that is, the modulation vector is only along the orthorhombic b{sup *} axis. This demonstrates unambiguously that La{sub 1.95}Sr{sub 0.05}CuO{sub 4} has a one-dimensional rather than two-dimensional static diagonal spin modulation at low temperatures, consistent with certain stripe models. From the L dependence we conclude that the spin correlations are predominantly two dimensional. We have also reexamined the x=0.04 crystal that previously was reported to show a single commensurate peak. By mounting the sample in the (H,K,0) zone, we have discovered that the x=0.04 sample in fact has the same IC structure as the x=0.05 sample. The incommensurability parameter {delta} for x=0.04 and 0.05, where {delta} is the distance from (1/2,1/2) in tetragonal reciprocal lattice units, follows the linear relation {delta}{approx_equal}x. These results demonstrate that the insulator to superconductor transition in the underdoped regime (0.05{<=}x{<=}0.06) in La{sub 2-x}Sr{sub x}CuO{sub 4} is coincident with a transition from diagonal to collinear static stripes at low temperatures thereby evincing the intimate coupling between the one-dimensional spin density modulation and the superconductivity. (c) 2000 The American Physical Society.
- OSTI ID:
- 20215337
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 61, Issue 5; Other Information: PBD: 1 Feb 2000; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SPIN GLASS STATE
NEUTRON DIFFRACTION
DOMAIN STRUCTURE
ELECTRICAL INSULATORS
PHASE TRANSFORMATIONS
MAGNETIC PROPERTIES
HIGH-BETA PLASMA
TRANSITION TEMPERATURE
CRITICAL TEMPERATURE
ORTHORHOMBIC LATTICES
LANTHANUM OXIDES
STRONTIUM OXIDES
COPPER OXIDES
EXPERIMENTAL DATA
THEORETICAL DATA