Robust ferromagnetic insulating and large exchange bias in LaMnO₃:CoO composite thin films

Abstract

Ferromagnetic insulators have received widespread attention for applications in novel low power consumption spintronic devices. Further optimizing the robust ferromagnetic insulating and developing multifunctional ferromagnetic insulator by integrating other magnetic property can not only ease or pave the way for actual application, but also provide an additional freedom degree for device designing. In this work, by introducing antiferromagnetic CoO into ferromagnetic insulator LaMnO3, we have constructed (1-x)LaMnO3:xCoO composite thin films. The films simultaneously show robust ferromagnetic insulator characteristics and large exchange bias. For x = 0.5 sample, the resistivity is 120 Ω·cm at 250 K while the magnetization is 100 emu/cm3 and the exchange bias field is -2200 Oe at 10 K. Especially, the blocking temperature is up to 140 K. Synchrotron radiation x-ray absorption spectroscopy reveals the coexistence of Mn3+, Mn2+, Co2+ and Co3+, arising from interfacial charge transfer and space charge/defect trapping, should be responsible for the enhanced and integrated multifunctional magnetic properties.

One-Stage Hydrothermal Growth and Characterization of Epitaxial LaMnO3 Films on SrTiO3 Substrate

“…Lanthanum manganite perovskite (LaMnO 3 ) and derivatives are appealing complex oxides for their functional applications in high-temperature solid oxide fuel cells (SOFCs) [ 1 , 2 , 3 ], supercapacitors [ 4 , 5 , 6 ], volatile organic compound (VOC) elimination [ 7 , 8 ], photocatalysis [ 9 ] and spintronic devices [ 10 ]. In particular, LaMnO 3 films have been subjected to intensive research as a highly competitive material for information storage since the discovery of the colossal magnetoresistance effect [ 11 , 12 , 13 , 14 ]. Bulk LaMnO 3 displays an orthorhombic ( ; a = 5.6792 Å, b = 7.7030 Å, c = 5.5410 Å) or a trigonal ( ; a = 5.6792 Å, b = 7.7030 Å, c = 5.5410 Å) symmetry at room temperature depending on the substitution or synthesis conditions [ 15 , 16 ].…”