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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Tuning the electronic and the crystalline structure of LaBi by pressure: From extreme magnetoresistance to superconductivity

Here, extreme magnetoresistance (XMR) in topological semimetals is a recent discovery which attracts attention due to its robust appearance in a growing number of materials. To search for a relation between XMR and superconductivity, we study the effect of pressure on LaBi. By increasing pressure, we observe the disappearance of XMR followed by the appearance of superconductivity at P ≈ 3.5 GPa. We find a region of coexistence between superconductivity and XMR in LaBi in contrast to other superconducting XMR materials. The suppression of XMR is correlated with increasing zero-field resistance instead of decreasing in-field resistance. At higher pressures, P ≈ 11 GPa, we find a structural transition from the face-centered cubic lattice to a primitive tetragonal lattice, in agreement with theoretical predictions. The relationship between extreme magnetoresistance, superconductivity, and structural transition in LaBi is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Tuning Perpendicular Magnetic Anisotropy by Oxygen Octahedral Rotations in ( La 1 – x Sr x MnO 3 ) / ( SrIrO 3 ) Superlattices

Here, perpendicular magnetic anisotropy (PMA) plays a critical role in the development of spintronics, thereby demanding new strategies to control PMA. Here we demonstrate a conceptually new type of interface induced PMA that is controlled by oxygen octahedral rotation. In superlattices comprised of La 1–x Sr x MnO 3 and SrIrO 3 , we find that all superlattices (0 ≤ x ≤ 1) exhibit ferromagnetism despite the fact that La 1–x Sr x MnO 3 is antiferromagnetic for x > 0.5. PMA as high as 4 × 10 6 erg/cm 3 is observed by increasing x and attributed to a decrease of oxygen octahedral rotation at interfaces. We also demonstrate that oxygen octahedral deformation cannot explain the trend in PMA. These results reveal a new degree of freedom to control PMA, enabling discovery of emergent magnetic textures and topological phenomena.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Magnetic-Field Tuning of Light-Induced Superconductivity in Striped La 2 – x Ba x CuO 4 [Magnetic-Field Tuning of Photo-Induced Superconductivity in Striped La 2 – x Ba x CuO 4 ]

Optical excitation of stripe-ordered La 2–x Ba x CuO 4 has been shown to transiently enhance superconducting tunneling between the CuO 2 planes. This effect was revealed by a blueshift, or by the appearance of a Josephson plasma resonance in the terahertz-frequency optical properties. Here, we show that this photoinduced state can be strengthened by the application of high external magnetic fields oriented along the c axis. For a 7 T field, we observe up to a tenfold enhancement in the transient interlayer phase correlation length, accompanied by a twofold increase in the relaxation time of the photoinduced state. These observations are highly surprising, since static magnetic fields suppress interlayer Josephson tunneling and stabilize stripe order at equilibrium. We interpret our data as an indication that optically enhanced interlayer coupling in La 2–x Ba x CuO 4 does not originate from a simple optical melting of stripes, as previously hypothesized. Furthermore, we speculate that the photoinduced state may emerge from activated tunneling between optically excited stripes in adjacent planes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗