Negative spin polarization in (La,Sr)CoO3 probed by a magnetic tunnel junction with (La,Sr)MnO3

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By using perovskite (La,Sr)MnO₃ (LSMO)-based magnetic tunnel junctions with LaAlO₃ barrier, we have experimentally revealed the spin state of (La,Sr)CoO₃ (LSCO) that was employed as the counterelectrode of the junctions. Inverse tunnel magnetoresistance (TMR) up to -14% was observed at 10 K in low-bias measurement. This indicates that t_2g↓ electrons are the majority at the Fermi level in the LSCO band structure, taking into account the half-metallic character of LSMO. The temperature dependence of the interfacial spin polarization of LSCO as deduced from the TMR ratio indicates the reduction of the Curie temperature at the interface by 70 K. The TMR ratio exhibits an asymmetric bias dependence in qualitative agreement with the calculated spin band structure of LSCO.

Published in:
Applied Physics Letters (Volume:91 , Issue: 19 )

Date of Publication: Nov 2007

Page(s):: 192504 - 192504-3
ISSN :: 0003-6951
Digital Object Identifier :: 10.1063/1.2806964
Product Type:: Journals & Magazines

Date of Current Version :: 18 June 2009
Issue Date :: Nov 2007

Author(s)

Ishii, Y.
Correlated Electron Research Center (CERC), The National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562, Japan and CREST Project, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
Yamada, H. ; Sato, H. ; Akoh, H. ; Kawasaki, M. ; Tokura, Y.