Related Experiment Video
Updated: Sep 11, 2025
07:03
Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
8.9K
Magnet-less gyrotropy using time-periodic modulation of permittivity
Optics Express
|August 13, 2025
Summary
Researchers demonstrate how time-varying dielectrics can emulate gyrotropy without magnetic fields. This breakthrough enables new electromagnetic effects using modulated electro-optic properties in nonlinear crystals.
Area of Science:
- Electromagnetics
- Materials Science
Background:
- Time-varying (TV) media have enabled significant electromagnetic effects like non-reciprocity and frequency conversion.
- The potential for achieving chirality and gyrotropy using TV dielectrics remains an open question.
Purpose of the Study:
- To investigate the emulation of gyrotropy in static, achiral, and non-gyrotropic crystals using time-modulated permittivity.
- To explore a method for achieving gyrotropy without magnetic materials or external magnetic bias fields.
Main Methods:
- Proposing a time-modulation of the permittivity tensor in a static achiral crystal.
- Analyzing the temporal rotation of the permittivity tensor's principal axes.
- Suggesting a realization via modulated electro-optic effects in nonlinear crystals.
Main Results:
- Successfully emulated gyrotropy in a non-magnetic, achiral medium through temporal modulation.
- Demonstrated that the emulated gyrotropy sustains circularly/elliptically polarized eigenmodes.
- Proposed a feasible experimental approach using nonlinear crystals.
Conclusions:
- Time-varying dielectrics offer a novel pathway to achieve gyrotropy without traditional magnetic components.
- The proposed method provides a practical route for realizing emulated gyrotropy in non-magnetic media.
- This research opens new possibilities for advanced electromagnetic devices and phenomena.
Related Concept Videos
01:22Motion Of A Charged Particle In A Magnetic Field
5.2K
A charged particle experiences a force when moving through a magnetic field. Consider the field to be uniform and the charged particle to move perpendicular to it. If the field is in a vacuum, the magnetic field is the dominant factor determining the motion. Since the magnetic force is perpendicular to the direction of motion, a charged particle follows a curved path. The particle continues to follow this curved path until it forms a complete circle. Another way to look at this is that the...
5.2K
01:28Magnetic Field Due To A Thin Straight Wire
5.0K
Consider an infinitely long straight wire carrying a current I. The magnetic field at point P at a distance a from the origin can be calculated using the Biot-Savart law.
5.0K
01:17Magnetic Damping
550
Eddy currents can produce significant drag on motion, called magnetic damping. For instance, when a metallic pendulum bob swings between the poles of a strong magnet, significant drag acts on the bob as it enters and leaves the field, quickly damping the motion.
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
550
01:23Magnetic Field due to Moving Charges
9.2K
A stationary charge creates and interacts with the electric field, while a moving charge creates a magnetic field.
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
9.2K
01:31Ferromagnetism
2.5K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
2.5K
01:30Paramagnetism
2.6K
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
2.6K