Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

AM: Magnetismus

AM 3: Magnetowiderstand I

AM 3.12: Vortrag

Montag, 26. März 2001, 17:15–17:30, S 5.2

STRUCTURE AND MAGNETOTRANSPORT OF COMPOSITE La-Ca-Mn-O FILMS — •Vasily Moshnyaga¹, Bernd Damaschke¹, Oleg Schapoval², Peter Petrenko², Alexander Belenchuk², and Konrad Samwer¹ — ¹1. Phys. Institut, Uni Goettingen, Goettingen — ²Institute of Applied Physics, Moldavian Academy of Sciences, Kishinev, Moldova

Composite thin films of (La-Ca-Mn-O)1-y(MgO)y (LCMOMO) (y=1-4) and (LCMO)1-x(La-Sr-Mn-O)x (LCSMO) (x=0-1) were grown on MgO substrates by metalorganic aerosol deposition. The LCMOMO and LCSMO show cubic c-axis lattice parameters c=0.385-0.396 and c=0.385-0.388 nm, respectively. Linear dependence of the lattice parameter on x for LCSMO proves a single phase without any phase separation between LCMO and LSMO. In contrast the LCMO-phase in LCMOMO separates well from that of MgO forming nanoparticles for large y. The Curie temperature, Tc, corresponds well to that of the metal-insulator transition, Tmi Tc, in LCMOMO films and decrease from 260 K to 120 K with increasing y. The ability to tune TMI in the range of 250-360 K by choosing the appropriate x for the LCSMO as well as to obtain MR(300K)=0.3 at B=1T for x=0.5 was demonstrated. Magnetic and electrical transport properties of composite LCMOMO films are discussed in terms of formation of LCMO particles in the MgO matrix. Tc and Tmi decrease significantly with decreasing of the particle size in accordance with corresponding increase of mechanical stress in LCMO nanoparticles.