Abstract
Ultrafast non-thermal manipulation of magnetization by light relies on either indirect coupling of the electric field component of the light with spins via spin-orbit interaction or direct coupling between the magnetic field component and spins. Here we propose a scenario for coupling between the electric field of light and spins via optical modification of the exchange interaction, one of the strongest quantum effects with strength of 103 Tesla. We demonstrate that this isotropic opto-magnetic effect, which can be called inverse magneto-refraction, is allowed in a material of any symmetry. Its existence is corroborated by the experimental observation of terahertz emission by spin resonances optically excited in a broad class of iron oxides with a canted spin configuration. From its strength we estimate that a sub-picosecond modification of the exchange interaction by laser pulses with fluence of about 1 mJ cm−2 acts as a pulsed effective magnetic field of 0.01 Tesla.
Highlights
Ultrafast non-thermal manipulation of magnetization by light relies on either indirect coupling of the electric field component of the light with spins via spin-orbit interaction or direct coupling between the magnetic field component and spins
We reported measurements of THz emission signals in the rare-earth orthoferrites[26] TmFeO3 and ErFeO3 which revealed the optical excitation of the high-frequency quasi-antiferromagnetic mode in these compounds along with the low-frequency quasiferromagnetic mode, another form of the antiferromagnetic resonance in canted antiferromagnets which involves the precession of the magnetization with no change in its length[25]
The magnetization lying in the plane of the sample was aligned horizontally by a constant bias magnetic field of B0.1 T
Summary
Ultrafast non-thermal manipulation of magnetization by light relies on either indirect coupling of the electric field component of the light with spins via spin-orbit interaction or direct coupling between the magnetic field component and spins. We propose a scenario for coupling between the electric field of light and spins via optical modification of the exchange interaction, one of the strongest quantum effects with strength of 103 Tesla. We demonstrate that this isotropic opto-magnetic effect, which can be called inverse magneto-refraction, is allowed in a material of any symmetry. From its strength we estimate that a sub-picosecond modification of the exchange interaction by laser pulses with fluence of about 1 mJ cm À 2 acts as a pulsed effective magnetic field of 0.01 Tesla. Correspondence and requests for materials should be addressed to R.V.M. The symmetric part of the exchange interaction between spins is responsible for the very existence of magnetic. Á jPth i;j adjacent ð^SiÂ^SjÞ, magnetic ions. characterized by a vector parameter D and called Dzyaloshinskii–Moriya interaction, gives rise to canted antiferromagnetism[2,3] in iron oxides
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