resumo
We determine the magnetic and magnetotransport properties of 33 nm thick Fe3O4 films epitaxially deposited by rf-magnetron sputtering on unpoled (011) [PbMg1/3Nb2/3O3](0.68) - [PbTiO3](0.32) (PMN-PT) substrates. The magnetoresistance (MR), as well as the magnetization reversal, strongly depend on the in-plane crystallographic direction of the epitaxial (011) Fe3O4 film and strain. When the magnetic field is applied along [100], the magnetization loops are slanted and the sign of the longitudinal MR changes from positive to negative around the Verwey transition at 125 K on cooling. Along the [01 (1) over bar] direction, the loops are square shaped and the MR is negative above the switching field across the whole temperature range, just increasing in absolute value when cooling from 300 K to 150 K. The value of the MR is found to be strongly affected by poling the PMN-PT substrate, decreasing in the [100] direction and slightly increasing in the [01 (1) over bar] direction upon poling, which results in a strained film.
palavras-chave
VERWEY TRANSITION; MAGNETORESISTANCE; MAGNETITE
categoria
Physics
autores
Tkach, A; Yazdi, MB; Foerster, M; Buttner, F; Vafaee, M; Fries, M; Klaui, M
nossos autores
Oleksandr Tkach
Investigador Auxiliaragradecimentos
Lambert Alff is acknowledged for the initiative to study the change of magnetic behavior across the Verwey transition of magnetite thin films provided by his group. This work was funded by the EU's 7th Framework Program IFOX (NMP3-LA-2010 246102), the Graduate School of Excellence MAINZ (GSC 266 Mainz), the German Science Foundation (DFG), and the ERC (2007-Stg 208162). A.T. acknowledges also funds by FEDER through Programa Operacional Factores de Competitividade-COMPETE and national funds through FCT-Fundacao para a Ciencia e Tecnologia within the CICECO project FCOMP-01-0124-FEDER-037271 (FCT Ref. PEst-C/CTM/LA0011/2013) and independent researcher grant IF/00602/2013.