Nanostructured Manganite Films Grown by Pulsed Injection MOCVD: Tuning Low- and High-Field Magnetoresistive Properties for Sensors Applications

Voitech Stankevic; Nerija Zurauskiene; Skirmantas Kersulis; Valentina Plausinaitiene; Rasuole Lukose; Jonas Klimantavicius; Sonata Tolvaišienė; Martynas Skapas; Algirdas Selskis; Saulius Balevicius

doi:10.3390/s22020605

Nanostructured Manganite Films Grown by Pulsed Injection MOCVD: Tuning Low- and High-Field Magnetoresistive Properties for Sensors Applications

Sensors (Basel). 2022 Jan 13;22(2):605. doi: 10.3390/s22020605.

Authors

Affiliations

¹ Center for Physical Sciences and Technology, 02300 Vilnius, Lithuania.
² Faculty of Electronics, Vilnius Gediminas Technical University, 10223 Vilnius, Lithuania.
³ Faculty of Chemistry and Geosciences, Vilnius University, 03225 Vilnius, Lithuania.
⁴ IHP-Leibniz-Institut für Innovative Mikroelektronik, 15236 Frankfurt (Oder), Germany.

Abstract

The results of colossal magnetoresistance (CMR) properties of La_0.83Sr_0.17Mn_1.21O₃ (LSMO) films grown by pulsed injection MOCVD technique onto various substrates are presented. The films with thicknesses of 360 nm and 60 nm grown on AT-cut single crystal quartz, polycrystalline Al₂O₃, and amorphous Si/SiO₂ substrates were nanostructured with column-shaped crystallites spread perpendicular to the film plane. It was found that morphology, microstructure, and magnetoresistive properties of the films strongly depend on the substrate used. The low-field MR at low temperatures (25 K) showed twice higher values (-31% at 0.7 T) for LSMO/quartz in comparison to films grown on the other substrates (-15%). This value is high in comparison to results published in literature for manganite films prepared without additional insulating oxides. The high-field MR measured up to 20 T at 80 K was also the highest for LSMO/quartz films (-56%) and demonstrated the highest sensitivity S = 0.28 V/T at B = 0.25 T (voltage supply 2.5 V), which is promising for magnetic sensor applications. It was demonstrated that Mn excess Mn/(La + Sr) = 1.21 increases the metal-insulator transition temperature of the films up to 285 K, allowing the increase in the operation temperature of magnetic sensors up to 363 K. These results allow us to fabricate CMR sensors with predetermined parameters in a wide range of magnetic fields and temperatures.

Keywords: MOCVD technology; colossal magnetoresistance; low field magnetoresistance; magnetic field sensors; manganite films; nanostructured thin films.