Abstract

The first-order hyperpolarizability β of magnetite nanoparticles in colloidal dispersion was measured in the presence and absence of an external magnetic field of magnitude H=800  G, applied with permanent neodymium magnets. For that, the (linear) attenuation spectrum was measured, and the nonlinear properties were obtained through the hyper-Rayleigh scattering technique. The attenuation spectrum is the same regardless of the external magnetic field, indicating that large aggregates of nanoparticles were not formed on our system. The first hyperpolarizability, on the other hand, increased when the incident beam polarization was parallel to the magnetic field lines and decreased when the directions were orthogonal, due to the alignment of crystallographic planes of the material when nanoparticles rotate in order to align their individual magnetic momentum, with respect to the external field. In the absence of a magnetic field, the hyperpolarizability βH=0=8.5(1)×1028  cm5/esu. For the parallel case, β=9.8(2)×1028  cm5/esu, while for the perpendicular configuration, β=8.1(1)×1028  cm5/esu. Defining the x axis of the particle reference frame parallel to the 111 crystallographic direction, which corresponds to the direction of easy magnetization, β=βxxx, and β corresponds to an average from βyyy and βzzz. When there is no external field applied, the nanoparticles are randomly oriented, and the measured hyperpolarizability corresponds to an average over the three orthogonal directions; that is, βH=13(β+2β)=8.6(1)×1028  cm5/esu, which is compatible with the measured value for the system without a magnetic field βH=0.

© 2018 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Influence of an external magnetic field in the two-photon absorption coefficient of magnetite nanoparticles in colloids and thin films

D. H. G. Espinosa, C. L. P. Oliveira, and A. M. Figueiredo Neto
J. Opt. Soc. Am. B 35(2) 346-355 (2018)

Unique determination of the hyperpolarizability tensor ratio through depolarized hyper-Rayleigh scattering under an external electric field

Jisoo Hwang, Byoungchoo Park, H. J. Chang, and J. W. Wu
J. Opt. Soc. Am. B 19(7) 1620-1626 (2002)

Measurements of the hyperpolarizability tensor by means of hyper-Rayleigh scattering

V. Ostroverkhov, R. G. Petschek, K. D. Singer, L. Sukhomlinova, R. J. Twieg, S.-X. Wang, and L. C. Chien
J. Opt. Soc. Am. B 17(9) 1531-1542 (2000)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (4)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (8)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription