Abstract
Imaging domain structure of antiferromagnetic DyFeO(3) reveals that intense laser excitation can control the temperature of the Morin transition from collinear to non-collinear spin state. Excitation of the antiferromagnet with femtosecond laser pulses with the central wavelength of 800 nm leads to a shift of the transition temperature over 1 K to higher values as if the light effectively cools the irradiated area down. It is suggested that the optical control of the Morin point can be a result of photo-ionization of Dy(3+) ions.
Highlights
Manipulation of magnetic order with the help of light is a counter-intuitive research subject and an issue of intense debates in many areas of science ranging from the physics of spintronics [1], magnonics [2], multiferroics [3] to organic chemistry [5]
It is argued that if an intense optical pumping ionizes Dy3+ ions bringing them into the Dy4+ state, it should lead to a substantial change of the effective exchange interaction between the spins of the Dy and Fe ions, affect the magnetic anisotropy experienced by the Fe-ions, change the temperature dependence of the magnetic anisotropy and shift the Morin point at which the spin reorientation occurs
We have found that if the crystal is excited with about 10 ultrashort laser pulses, the Morin temperature of the irradiated area changes
Summary
Manipulation of magnetic order with the help of light is a counter-intuitive research subject and an issue of intense debates in many areas of science ranging from the physics of spintronics [1], magnonics [2], multiferroics [3] to organic chemistry [5]. The action of electric field on electronic charges, being the largest perturbation in physics of light-matter interaction, conserves the spin of electron and an efficient control of magnetic properties of media with light is counter-intuitive Despite this fact, several effective mechanisms of such a control have been demonstrated up to date and antiferromagnetic rare-earth orthoferrites played in these studies an important role. It was suggested that laser excitation of the chargetransfer transitions in the rare-earth orthoferrites can effectively lead to optical modification of the spin-spin exchange interactions in these materials [15] This observation can be seen as the inverse magnetorefractive effect [16,17]. It is argued that if an intense optical pumping ionizes Dy3+ ions bringing them into the Dy4+ state, it should lead to a substantial change of the effective exchange interaction between the spins of the Dy and Fe ions, affect the magnetic anisotropy experienced by the Fe-ions, change the temperature dependence of the magnetic anisotropy and shift the Morin point at which the spin reorientation occurs
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