%0 Journal Article
%4 sid.inpe.br/mtc-m21b/2016/06.02.18.44
%2 sid.inpe.br/mtc-m21b/2016/06.02.18.44.30
%@doi 10.1103/PhysRevB.93.201201
%@issn 1098-0121
%T Light-induced polaron magnetization in EuTe at temperatures reaching 150 K
%D 2016
%8 May
%9 journal article
%A Henriques, A. B.,
%A Galgano, G. D.,
%A Rappl, Paulo Henrique de Oliveira,
%A Abramof, Eduardo,
%@affiliation Universidade de São Paulo (USP)
%@affiliation Universidade de São Paulo (USP)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@electronicmailaddress
%@electronicmailaddress
%@electronicmailaddress paulo.rappl@inpe.br
%@electronicmailaddress eduardo.abramof@inpe.br
%B Physical Review B: Condensed Matter and Materials Physics
%V 93
%N 20
%P 201201
%X We demonstrate that light creates a highly magnetized region in a magnetic semiconductor far above its critical temperature. A near-gap photon generates a quasiparticle of nonzero magnetic moment, named magnetic polaron, which is constituted by the photoexcited electron and about 1000 spin-polarized lattice atoms surrounding the photoexcited electron. The photoinduced magnetization follows a Langevin function, whose shape uniquely determines the magnetic moment of an individual polaron. In EuTe at 5 K the magnetic moment reaches a giant value of over 500 Bohr magnetons, thus the photoinduced magnetization saturates with a magnetic field of only 50 mT, which characterizes the magnetic polaron system as superparamagnetic. The polaron has an average lifetime of 15μs. When temperature is increased its magnetic moment decreases, but at 150 K it still has a large value of about 80 Bohr magnetons. The paramagnet of polarons is fully controlled by light. Because the magnetic polaron affects only spin orientation, but not the charge distribution, in the superparamagnetic state the ideal optical quality of the host semiconductor is preserved.
%@language en