Recent advances in ultrashort-pulsed laser technology have enabled the ultrafast control of magnetization by light. This has created a new field that is attracting remarkable attention because of both the scientific interest and its potential applications, such as the coherent control of the precession of a single spin1
or spin ensemble2
. Several experiments have revealed a wide variety of physics within this context, for example, ultrafast control through a nonlinear optical process2
or by employing the magnetic component of terahertz (THz) electromagnetic pulses9
. Previous studies focused primarily on the control of the phase and amplitude of a single magnetic oscillation mode. In this case, the three-dimensional trajectory of magnetization motion cannot be altered. As a next step, we propose a new technique to control magnetization in a multidimensional space to fully employ its vectorial properties. This technique can lead to further applications, such as storing multiple pieces of information in a single storage element and the implementation of novel quantum processing using light-spin interactions.
To realize such vectorial control, it is necessary to independently address the phase and amplitude of multiple degenerate modes that constitute complete bases for describing magnetization vector dynamics, as shown in . For example, consider a magnetization vector that behaves as an isotropic harmonic oscillator in a two-dimensional space. The motion of the magnetization is described by a linear combination of two degenerate orthogonal modes labelled x and y (), and their relative phases and amplitudes determine its trajectory.
Schematic illustrations of the experiment.
Here we demonstrate a full manipulation of two-dimensional magnetic oscillations in an antiferromagnetic NiO crystal by employing a pair of polarization-twisted optical pulses. This technique opens new horizons for the optical manipulation of magnetization vectors.