Abstract
The absence of net magnetization inside antiferromagnetic domains has made the control of their spatial distribution quite challenging. Here we experimentally demonstrate an optical method for controlling antiferromagnetic domain distributions in MnF2. Reduced crystalline symmetry can couple an order parameter with non-conjugate external stimuli. In the case of MnF2, time-reversal symmetry is macroscopically broken reflecting the different orientations of the two magnetic sublattices. Thus, it exhibits different absorption coefficients between two orthogonal linear polarizations below its antiferromagnetic transition temperature under an external magnetic field. Illumination with linearly polarized laser light under this condition selectively destructs the formation of a particular antiferromagnetic order via heating. As a result, the other antiferromagnetic order is favoured inside the laser spot, achieving spatially localized selection of an antiferromagnetic order. Applications to control of interface states at antiferromagnetic domain boundaries, exchange bias and control of spin currents are expected.
Highlights
The absence of net magnetization inside antiferromagnetic domains has made the control of their spatial distribution quite challenging
In the simple case of a two-sublattice antiferromagnet, there are two possible states: one sublattice is occupied by up spins and the other by down spins—or vice versa. This bistable magnetism is a manifestation of spontaneous symmetry breaking
We employ the coupling between antiferromagnetic order and asymmetric optical absorption in an antiferromagnetic material without time-reversal symmetry
Summary
The absence of net magnetization inside antiferromagnetic domains has made the control of their spatial distribution quite challenging. The control of the spatial distribution of these antiferromagnetic domains is of particular importance[1,2,3,4] because they determine the functionalities of antiferromagnetic materials with existing and potential applications, such as exchange coupling between adjacent antiferromagnetic and ferromagnetic orders[5], dense non-volatile memory[6,7] and conductivity by topologically protected metallic states confined to the antiferromagnetic domain boundaries[8,9]. Ferromagnetic domains are controlled via illumination with a circularly polarized light The mechanism behind this phenomenon is considered to be combinations of various effects, such as the inverse Faraday effect[14,15], the destruction of magnetic ordering through selective absorption due to magnetic circular dichroism (MCD)[16,17] and optical spin pumping[18]. The magnetic ordering can be chosen by the polarization state of the pumping light, with the other conditions kept the same
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